Opened 5 years ago

Last modified 3 years ago

#1878 new defect

Seeking causes later packets to be thrown away

Reported by: mbradshaw Owned by:
Priority: normal Component: undetermined
Version: git-master Keywords: seek
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no

Description

Summary of the bug:
Seeking causes certain packets to be thrown away, depending on which stream was sought. This is either a bug in the code, or an undocumented but critical "feature." I am unsure of which.

Link to sample file:
https://docs.google.com/uc?id=0BxWx_dIBnyRoSnMyTFNGOHR1c2c&export=download (321 MB)
I'm sorry it's not a perfectly direct link. Google Drive requires you to acknowledge that it hasn't been scanned for viruses because of its file size.

How to reproduce:
If I seek using a stream index of 1 (the audio stream), av_read_frame() skips the first two video packets, but if I seek using a stream index of 0 (the video stream), av_read_frame() does not skip the first two video packets. ffprobe shows that the first several packets in the file belong to the video stream, and I was hoping and assuming that seeking back to the very first packet in the file (which is why I was seeking by the audio stream index) would be a valid way to properly reset all streams to the beginning. However, this issue causes the first bit of video to be skipped, which is not acceptable in my situation.

Here is some sample code I wrote to illustrate the problem. There is a significant difference in output when seeking by stream index of 0 and seeking by stream index of 1.

#include <stdio.h>

// Just remove the extern "C" part to compile as C
extern "C"
{
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswresample/swresample.h>
}

static void decodeFirstFrame(AVFormatContext* formatContext, AVStream* videoStream, AVFrame* frame)
{
    AVPacket packet;
    int packetNumber;
    int frameFinished;
    int result;

    packetNumber = 0;
    av_init_packet(&packet);
    while (av_read_frame(formatContext, &packet) == 0)
    {
        printf("packet #: %7d\tdts: %7d\ttype: %s\n", packetNumber++,
            (int)packet.dts, (packet.stream_index == videoStream->index) ? "video *" : "audio");
        if (packet.stream_index == videoStream->index)
        {
            frameFinished = 0;
            result = avcodec_decode_video2(videoStream->codec, frame, &frameFinished, &packet);

            if (result >= 0 && frameFinished)
            {
                printf("Got video frame at time %d\n", (int)av_frame_get_best_effort_timestamp(frame));
                av_free_packet(&packet);
                break;
            }
        }

        av_free_packet(&packet);
    }
}

int main(int argc, char** argv)
{
    AVFrame* frame;
    AVFormatContext* formatContext;
    AVStream* videoStream;
    AVCodecContext* codecContext;

    av_register_all();

    frame = avcodec_alloc_frame();
    if (!frame)
    {
        printf("Error allocating the frame\n");
        return 1;
    }

    formatContext = NULL;
    if (avformat_open_input(&formatContext, "SIMPSONS_D2-CallOfTheSimpsons.m4v", NULL, NULL) != 0)
    {
        av_free(frame);
        printf("Error opening the file\n");
        return 1;
    }

    if (avformat_find_stream_info(formatContext, NULL) < 0)
    {
        av_free(frame);
        avformat_close_input(&formatContext);
        printf("Error finding the stream info\n");
        return 1;
    }
    
    videoStream = NULL;
    for (unsigned int i = 0; i < formatContext->nb_streams; ++i)
    {
        if (formatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
        {
            videoStream = formatContext->streams[i];
            break;
        }
    }

    if (videoStream == NULL)
    {
        av_free(frame);
        avformat_close_input(&formatContext);
        printf("Could not find any video stream in the file\n");
        return 1;
    }

    codecContext = videoStream->codec;
    codecContext->codec = avcodec_find_decoder(codecContext->codec_id);
    if (codecContext->codec == NULL)
    {
        av_free(frame);
        avformat_close_input(&formatContext);
        printf("Couldn't find a proper decoder\n");
        return 1;
    }
    else if (avcodec_open2(codecContext, codecContext->codec, NULL) != 0)
    {
        av_free(frame);
        avformat_close_input(&formatContext);
        printf("Couldn't open the context with the decoder\n");
        return 1;
    }

    decodeFirstFrame(formatContext, videoStream, frame);
    
    avcodec_flush_buffers(codecContext);
    printf("seek result: %d\n",
           av_seek_frame(formatContext, 0, -2000000000, AVSEEK_FLAG_BACKWARD | AVSEEK_FLAG_ANY));
    
    decodeFirstFrame(formatContext, videoStream, frame);

    av_free(frame);
    avcodec_close(codecContext);
    avformat_close_input(&formatContext);
    return 0;
}

Output from first call to decodeFirstFrame():

packet #:       0       dts:       0    type: audio
packet #:       1       dts:    1024    type: audio
packet #:       2       dts:    2048    type: audio
packet #:       3       dts:    3072    type: audio
packet #:       4       dts:    4096    type: audio
packet #:       5       dts:    5120    type: audio
packet #:       6       dts:    6144    type: audio
packet #:       7       dts:   -6006    type: video *
packet #:       8       dts:   -3003    type: video *
packet #:       9       dts:       0    type: video *
packet #:      10       dts:    3003    type: video *
packet #:      11       dts:    7168    type: audio
packet #:      12       dts:    8192    type: audio
packet #:      13       dts:    9216    type: audio
packet #:      14       dts:   10240    type: audio
packet #:      15       dts:   11264    type: audio
packet #:      16       dts:   12288    type: audio
packet #:      17       dts:   13312    type: audio
packet #:      18       dts:    6006    type: video *
Got video frame at time 0

Seek result:

seek result: 0

Output from second call to decodeFirstFrame() after performing av_seek_frame() with stream_index = 1 (note it skips the first two video packets, which have DTS = -6006 and -3003) (these results are undesirable):

packet #:       0       dts:       0    type: audio
packet #:       1       dts:    1024    type: audio
packet #:       2       dts:    2048    type: audio
packet #:       3       dts:    3072    type: audio
packet #:       4       dts:    4096    type: audio
packet #:       5       dts:    5120    type: audio
packet #:       6       dts:    6144    type: audio
packet #:       7       dts:       0    type: video *
packet #:       8       dts:    3003    type: video *
[h264 @ 0072fa80] reference picture missing during reorder
[h264 @ 0072fa80] reference picture missing during reorder
[h264 @ 0072fa80] reference picture missing during reorder
[h264 @ 0072fa80] Missing reference picture
[h264 @ 0072fa80] decode_slice_header error
[h264 @ 0072fa80] concealing 1350 DC, 1350 AC, 1350 MV errors in P frame
[h264 @ 00b6f800] mmco: unref short failure
packet #:       9       dts:    7168    type: audio
packet #:      10       dts:    8192    type: audio
[h264 @ 00b6f800] packet #:      11     dts:    9216    type: audio
packet #:      12       dts:   10240    type: audio
Missing reference picture
packet #:      13       dts:   11264    type: audio
packet #:      14       dts:   12288    type: audio
packet #:      15       dts:   13312    type: audio
packet #:      16       dts:    6006    type: video *
packet #:      17       dts:    9009    type: video *
[h264 @ 00682de0] reference picture missing during reorder
[h264 @ 00682de0] reference picture missing during reorder
[h264 @ 00682de0] Missing reference picture
[h264 @ 00682de0] Missing reference picture
[h264 @ 0072fa80] mmco: unref short failure
packet #:      18       dts:   12012    type: video *
packet #:      19       dts:   15015    type: video *
[h264 @ 00b6f800] reference picture missing during reorder
[h264 @ 00b6f800] Missing reference picture
packet #:      20       dts:   18018    type: video *
packet #:      21       dts:   21021    type: video *
packet #:      22       dts:   24024    type: video *
packet #:      23       dts:   27027    type: video *
packet #:      24       dts:   14336    type: audio
packet #:      25       dts:   15360    type: audio
packet #:      26       dts:   16384    type: audio
packet #:      27       dts:   17408    type: audio
packet #:      28       dts:   18432    type: audio
packet #:      29       dts:   19456    type: audio
packet #:      30       dts:   20480    type: audio
packet #:      31       dts:   30030    type: video *
packet #:      32       dts:   33033    type: video *
packet #:      33       dts:   36036    type: video *
packet #:      34       dts:   39039    type: video *
packet #:      35       dts:   21504    type: audio
packet #:      36       dts:   22528    type: audio
packet #:      37       dts:   23552    type: audio
packet #:      38       dts:   24576    type: audio
packet #:      39       dts:   25600    type: audio
packet #:      40       dts:   26624    type: audio
packet #:      41       dts:   27648    type: audio
packet #:      42       dts:   42042    type: video *
packet #:      43       dts:   45045    type: video *
packet #:      44       dts:   48048    type: video *
packet #:      45       dts:   51051    type: video *
packet #:      46       dts:   28672    type: audio
packet #:      47       dts:   29696    type: audio
packet #:      48       dts:   30720    type: audio
packet #:      49       dts:   31744    type: audio
packet #:      50       dts:   32768    type: audio
packet #:      51       dts:   33792    type: audio
packet #:      52       dts:   34816    type: audio
packet #:      53       dts:   54054    type: video *
packet #:      54       dts:   57057    type: video *
packet #:      55       dts:   60060    type: video *
packet #:      56       dts:   63063    type: video *
packet #:      57       dts:   35840    type: audio
packet #:      58       dts:   36864    type: audio
packet #:      59       dts:   37888    type: audio
packet #:      60       dts:   38912    type: audio
packet #:      61       dts:   39936    type: audio
packet #:      62       dts:   40960    type: audio
packet #:      63       dts:   41984    type: audio
packet #:      64       dts:   66066    type: video *
packet #:      65       dts:   69069    type: video *
packet #:      66       dts:   72072    type: video *
packet #:      67       dts:   75075    type: video *
packet #:      68       dts:   43008    type: audio
packet #:      69       dts:   44032    type: audio
packet #:      70       dts:   -6006    type: audio
packet #:      71       dts:   45056    type: audio
packet #:      72       dts:   46080    type: audio
packet #:      73       dts:   47104    type: audio
packet #:      74       dts:   48128    type: audio
packet #:      75       dts:   49152    type: audio
packet #:      76       dts:   78078    type: video *
packet #:      77       dts:   81081    type: video *
packet #:      78       dts:   84084    type: video *
packet #:      79       dts:   87087    type: video *
packet #:      80       dts:   50176    type: audio
packet #:      81       dts:   51200    type: audio
packet #:      82       dts:   52224    type: audio
packet #:      83       dts:   53248    type: audio
packet #:      84       dts:   54272    type: audio
packet #:      85       dts:   55296    type: audio
packet #:      86       dts:   56320    type: audio
packet #:      87       dts:   90090    type: video *
packet #:      88       dts:   93093    type: video *
packet #:      89       dts:   96096    type: video *
packet #:      90       dts:   99099    type: video *
packet #:      91       dts:   57344    type: audio
packet #:      92       dts:   58368    type: audio
packet #:      93       dts:   59392    type: audio
packet #:      94       dts:   60416    type: audio
packet #:      95       dts:   61440    type: audio
packet #:      96       dts:   62464    type: audio
packet #:      97       dts:   63488    type: audio
packet #:      98       dts:  102102    type: video *
packet #:      99       dts:  105105    type: video *
packet #:     100       dts:  108108    type: video *
packet #:     101       dts:  111111    type: video *
packet #:     102       dts:  114114    type: video *
packet #:     103       dts:  117117    type: video *
packet #:     104       dts:  120120    type: video *
packet #:     105       dts:  123123    type: video *
packet #:     106       dts:   64512    type: audio
packet #:     107       dts:   65536    type: audio
packet #:     108       dts:   66560    type: audio
packet #:     109       dts:   67584    type: audio
packet #:     110       dts:   68608    type: audio
packet #:     111       dts:   69632    type: audio
packet #:     112       dts:   70656    type: audio
packet #:     113       dts:  126126    type: video *
packet #:     114       dts:  129129    type: video *
packet #:     115       dts:  132132    type: video *
packet #:     116       dts:  135135    type: video *
packet #:     117       dts:   71680    type: audio
packet #:     118       dts:   72704    type: audio
packet #:     119       dts:   73728    type: audio
packet #:     120       dts:   74752    type: audio
packet #:     121       dts:   75776    type: audio
packet #:     122       dts:   76800    type: audio
packet #:     123       dts:   77824    type: audio
packet #:     124       dts:  138138    type: video *
packet #:     125       dts:  141141    type: video *
packet #:     126       dts:  144144    type: video *
packet #:     127       dts:  147147    type: video *
packet #:     128       dts:   78848    type: audio
packet #:     129       dts:   79872    type: audio
packet #:     130       dts:   80896    type: audio
packet #:     131       dts:   81920    type: audio
packet #:     132       dts:   82944    type: audio
packet #:     133       dts:   83968    type: audio
packet #:     134       dts:   84992    type: audio
packet #:     135       dts:   86016    type: audio
packet #:     136       dts:   87040    type: audio
packet #:     137       dts:   88064    type: audio
packet #:     138       dts:   89088    type: audio
packet #:     139       dts:   90112    type: audio
packet #:     140       dts:   91136    type: audio
packet #:     141       dts:   92160    type: audio
packet #:     142       dts:  150150    type: video *
packet #:     143       dts:  153153    type: video *
packet #:     144       dts:  156156    type: video *
packet #:     145       dts:  159159    type: video *
packet #:     146       dts:  162162    type: video *
packet #:     147       dts:  165165    type: video *
packet #:     148       dts:  168168    type: video *
packet #:     149       dts:  171171    type: video *
packet #:     150       dts:   93184    type: audio
packet #:     151       dts:   94208    type: audio
packet #:     152       dts:   95232    type: audio
packet #:     153       dts:   96256    type: audio
packet #:     154       dts:   97280    type: audio
packet #:     155       dts:   98304    type: audio
packet #:     156       dts:   99328    type: audio
packet #:     157       dts:  174174    type: video *
packet #:     158       dts:  177177    type: video *
packet #:     159       dts:  180180    type: video *
packet #:     160       dts:  183183    type: video *
packet #:     161       dts:  100352    type: audio
packet #:     162       dts:  101376    type: audio
packet #:     163       dts:  102400    type: audio
packet #:     164       dts:  103424    type: audio
packet #:     165       dts:  104448    type: audio
packet #:     166       dts:  105472    type: audio
packet #:     167       dts:  106496    type: audio
packet #:     168       dts:  186186    type: video *
packet #:     169       dts:  189189    type: video *
packet #:     170       dts:  192192    type: video *
packet #:     171       dts:  195195    type: video *
packet #:     172       dts:  107520    type: audio
packet #:     173       dts:  108544    type: audio
packet #:     174       dts:  109568    type: audio
packet #:     175       dts:  110592    type: audio
packet #:     176       dts:  111616    type: audio
packet #:     177       dts:  112640    type: audio
packet #:     178       dts:  113664    type: audio
packet #:     179       dts:  198198    type: video *
packet #:     180       dts:  201201    type: video *
packet #:     181       dts:  204204    type: video *
packet #:     182       dts:  207207    type: video *
packet #:     183       dts:  114688    type: audio
packet #:     184       dts:  115712    type: audio
packet #:     185       dts:  116736    type: audio
packet #:     186       dts:  117760    type: audio
packet #:     187       dts:  118784    type: audio
packet #:     188       dts:  119808    type: audio
packet #:     189       dts:  120832    type: audio
packet #:     190       dts:  210210    type: video *
packet #:     191       dts:  213213    type: video *
packet #:     192       dts:  216216    type: video *
packet #:     193       dts:  219219    type: video *
packet #:     194       dts:  121856    type: audio
packet #:     195       dts:  122880    type: audio
packet #:     196       dts:  123904    type: audio
packet #:     197       dts:  124928    type: audio
packet #:     198       dts:  125952    type: audio
packet #:     199       dts:  126976    type: audio
packet #:     200       dts:  128000    type: audio
packet #:     201       dts:  222222    type: video *
packet #:     202       dts:  225530    type: video *
packet #:     203       dts:  228533    type: video *
packet #:     204       dts:  231536    type: video *
packet #:     205       dts:  129024    type: audio
packet #:     206       dts:  130048    type: audio
packet #:     207       dts:  131072    type: audio
packet #:     208       dts:  132096    type: audio
packet #:     209       dts:  133120    type: audio
packet #:     210       dts:  134144    type: audio
packet #:     211       dts:  135168    type: audio
packet #:     212       dts:  234539    type: video *
packet #:     213       dts:  237542    type: video *
packet #:     214       dts:  240545    type: video *
packet #:     215       dts:  243548    type: video *
packet #:     216       dts:  136192    type: audio
packet #:     217       dts:  137216    type: audio
packet #:     218       dts:  138240    type: audio
packet #:     219       dts:  139264    type: audio
packet #:     220       dts:  140288    type: audio
packet #:     221       dts:  141312    type: audio
packet #:     222       dts:  142336    type: audio
packet #:     223       dts:  246551    type: video *
packet #:     224       dts:  249554    type: video *
packet #:     225       dts:  252557    type: video *
packet #:     226       dts:  255560    type: video *
packet #:     227       dts:  258563    type: video *
packet #:     228       dts:  261566    type: video *
packet #:     229       dts:  264569    type: video *
packet #:     230       dts:  267572    type: video *
packet #:     231       dts:  143360    type: audio
packet #:     232       dts:  144384    type: audio
packet #:     233       dts:  145408    type: audio
packet #:     234       dts:  146432    type: audio
packet #:     235       dts:  147456    type: audio
packet #:     236       dts:  148480    type: audio
packet #:     237       dts:  149504    type: audio
packet #:     238       dts:  150528    type: audio
packet #:     239       dts:  151552    type: audio
packet #:     240       dts:  152576    type: audio
packet #:     241       dts:  153600    type: audio
packet #:     242       dts:  154624    type: audio
packet #:     243       dts:  155648    type: audio
packet #:     244       dts:  156672    type: audio
packet #:     245       dts:  270575    type: video *
packet #:     246       dts:  273578    type: video *
packet #:     247       dts:  277334    type: video *
packet #:     248       dts:  281087    type: video *
packet #:     249       dts:  157696    type: audio
packet #:     250       dts:  158720    type: audio
packet #:     251       dts:  159744    type: audio
packet #:     252       dts:  160768    type: audio
packet #:     253       dts:  161792    type: audio
packet #:     254       dts:  162816    type: audio
packet #:     255       dts:  163840    type: audio
packet #:     256       dts:  284840    type: video *
packet #:     257       dts:  288593    type: video *
packet #:     258       dts:  291596    type: video *
packet #:     259       dts:  294599    type: video *
packet #:     260       dts:  297602    type: video *
packet #:     261       dts:  300605    type: video *
packet #:     262       dts:  303608    type: video *
packet #:     263       dts:  306611    type: video *
packet #:     264       dts:  164864    type: audio
packet #:     265       dts:  165888    type: audio
packet #:     266       dts:  166912    type: audio
packet #:     267       dts:  167936    type: audio
packet #:     268       dts:  168960    type: audio
packet #:     269       dts:  169984    type: audio
packet #:     270       dts:  171008    type: audio
packet #:     271       dts:  309614    type: video *
packet #:     272       dts:  312617    type: video *
packet #:     273       dts:  315620    type: video *
packet #:     274       dts:  318623    type: video *
packet #:     275       dts:  172032    type: audio
packet #:     276       dts:  173056    type: audio
packet #:     277       dts:  174080    type: audio
packet #:     278       dts:  175104    type: audio
packet #:     279       dts:  176128    type: audio
packet #:     280       dts:  177152    type: audio
packet #:     281       dts:  178176    type: audio
packet #:     282       dts:  321626    type: video *
packet #:     283       dts:  324629    type: video *
packet #:     284       dts:  327632    type: video *
packet #:     285       dts:  330635    type: video *
packet #:     286       dts:  179200    type: audio
packet #:     287       dts:  180224    type: audio
packet #:     288       dts:  181248    type: audio
packet #:     289       dts:  182272    type: audio
packet #:     290       dts:  183296    type: audio
packet #:     291       dts:  184320    type: audio
packet #:     292       dts:  185344    type: audio
packet #:     293       dts:  333638    type: video *
packet #:     294       dts:  336641    type: video *
packet #:     295       dts:  339644    type: video *
packet #:     296       dts:  342647    type: video *
packet #:     297       dts:  186368    type: audio
packet #:     298       dts:  187392    type: audio
packet #:     299       dts:  188416    type: audio
packet #:     300       dts:  189440    type: audio
packet #:     301       dts:  190464    type: audio
packet #:     302       dts:  191488    type: audio
packet #:     303       dts:  192512    type: audio
packet #:     304       dts:  345650    type: video *
packet #:     305       dts:  348653    type: video *
packet #:     306       dts:  351656    type: video *
packet #:     307       dts:  354659    type: video *
packet #:     308       dts:  193536    type: audio
packet #:     309       dts:  194560    type: audio
packet #:     310       dts:  195584    type: audio
packet #:     311       dts:  196608    type: audio
packet #:     312       dts:  197632    type: audio
packet #:     313       dts:  198656    type: audio
packet #:     314       dts:  199680    type: audio
packet #:     315       dts:  357662    type: video *
packet #:     316       dts:  360665    type: video *
packet #:     317       dts:  363668    type: video *
packet #:     318       dts:  366671    type: video *
packet #:     319       dts:  200704    type: audio
packet #:     320       dts:  201728    type: audio
packet #:     321       dts:  202752    type: audio
packet #:     322       dts:  203776    type: audio
packet #:     323       dts:  204800    type: audio
packet #:     324       dts:  205824    type: audio
packet #:     325       dts:  206848    type: audio
packet #:     326       dts:  369674    type: video *
packet #:     327       dts:  372677    type: video *
packet #:     328       dts:  375680    type: video *
packet #:     329       dts:  378683    type: video *
packet #:     330       dts:  207872    type: audio
packet #:     331       dts:  208896    type: audio
packet #:     332       dts:  209920    type: audio
packet #:     333       dts:  210944    type: audio
packet #:     334       dts:  211968    type: audio
packet #:     335       dts:  212992    type: audio
packet #:     336       dts:  214016    type: audio
packet #:     337       dts:  381686    type: video *
packet #:     338       dts:  384689    type: video *
packet #:     339       dts:  387692    type: video *
packet #:     340       dts:  390695    type: video *
packet #:     341       dts:  215040    type: audio
packet #:     342       dts:  216064    type: audio
packet #:     343       dts:  217088    type: audio
packet #:     344       dts:  218112    type: audio
packet #:     345       dts:  219136    type: audio
packet #:     346       dts:  220160    type: audio
packet #:     347       dts:  221184    type: audio
packet #:     348       dts:  393698    type: video *
packet #:     349       dts:  397454    type: video *
packet #:     350       dts:  401207    type: video *
packet #:     351       dts:  404960    type: video *
packet #:     352       dts:  222208    type: audio
packet #:     353       dts:  223232    type: audio
packet #:     354       dts:  224256    type: audio
packet #:     355       dts:  225280    type: audio
packet #:     356       dts:  226304    type: audio
packet #:     357       dts:  227328    type: audio
packet #:     358       dts:  228352    type: audio
packet #:     359       dts:  408713    type: video *
packet #:     360       dts:  411716    type: video *
packet #:     361       dts:  414719    type: video *
packet #:     362       dts:  417722    type: video *
packet #:     363       dts:  229376    type: audio
packet #:     364       dts:  230400    type: audio
packet #:     365       dts:  231424    type: audio
packet #:     366       dts:  232448    type: audio
packet #:     367       dts:  233472    type: audio
packet #:     368       dts:  234496    type: audio
packet #:     369       dts:  235520    type: audio
packet #:     370       dts:  420725    type: video *
packet #:     371       dts:  423728    type: video *
packet #:     372       dts:  427484    type: video *
packet #:     373       dts:  431237    type: video *
packet #:     374       dts:  236544    type: audio
packet #:     375       dts:  237568    type: audio
packet #:     376       dts:  238592    type: audio
packet #:     377       dts:  239616    type: audio
packet #:     378       dts:  240640    type: audio
packet #:     379       dts:  241664    type: audio
packet #:     380       dts:  242688    type: audio
packet #:     381       dts:  434990    type: video *
packet #:     382       dts:  438743    type: video *
packet #:     383       dts:  441746    type: video *
packet #:     384       dts:  444749    type: video *
packet #:     385       dts:  243712    type: audio
packet #:     386       dts:  244736    type: audio
packet #:     387       dts:  245760    type: audio
packet #:     388       dts:  246784    type: audio
packet #:     389       dts:  247808    type: audio
packet #:     390       dts:  248832    type: audio
packet #:     391       dts:  249856    type: audio
packet #:     392       dts:  447752    type: video *
packet #:     393       dts:  450755    type: video *
packet #:     394       dts:  453758    type: video *
packet #:     395       dts:  457514    type: video *
packet #:     396       dts:  250880    type: audio
packet #:     397       dts:  251904    type: audio
packet #:     398       dts:  252928    type: audio
packet #:     399       dts:  253952    type: audio
packet #:     400       dts:  254976    type: audio
packet #:     401       dts:  256000    type: audio
packet #:     402       dts:  257024    type: audio
packet #:     403       dts:  461267    type: video *
packet #:     404       dts:  465020    type: video *
packet #:     405       dts:  468773    type: video *
packet #:     406       dts:  471776    type: video *
packet #:     407       dts:  258048    type: audio
packet #:     408       dts:  259072    type: audio
packet #:     409       dts:  260096    type: audio
packet #:     410       dts:  261120    type: audio
packet #:     411       dts:  262144    type: audio
packet #:     412       dts:  263168    type: audio
packet #:     413       dts:  264192    type: audio
packet #:     414       dts:  474779    type: video *
packet #:     415       dts:  477782    type: video *
packet #:     416       dts:  480785    type: video *
packet #:     417       dts:  483788    type: video *
packet #:     418       dts:  487544    type: video *
packet #:     419       dts:  491297    type: video *
packet #:     420       dts:  495050    type: video *
packet #:     421       dts:  498803    type: video *
packet #:     422       dts:  265216    type: audio
packet #:     423       dts:  266240    type: audio
packet #:     424       dts:  267264    type: audio
packet #:     425       dts:  268288    type: audio
packet #:     426       dts:  269312    type: audio
packet #:     427       dts:  270336    type: audio
packet #:     428       dts:  271360    type: audio
packet #:     429       dts:  272384    type: audio
packet #:     430       dts:  273408    type: audio
packet #:     431       dts:  274432    type: audio
packet #:     432       dts:  275456    type: audio
packet #:     433       dts:  276480    type: audio
packet #:     434       dts:  277504    type: audio
packet #:     435       dts:  278528    type: audio
packet #:     436       dts:  502559    type: video *
packet #:     437       dts:  506312    type: video *
packet #:     438       dts:  510065    type: video *
packet #:     439       dts:  513818    type: video *
packet #:     440       dts:  279552    type: audio
packet #:     441       dts:  280576    type: audio
packet #:     442       dts:  281600    type: audio
packet #:     443       dts:  282624    type: audio
packet #:     444       dts:  283648    type: audio
packet #:     445       dts:  284672    type: audio
packet #:     446       dts:  285696    type: audio
packet #:     447       dts:  286720    type: audio
packet #:     448       dts:  287744    type: audio
packet #:     449       dts:  288768    type: audio
packet #:     450       dts:  289792    type: audio
packet #:     451       dts:  290816    type: audio
packet #:     452       dts:  291840    type: audio
packet #:     453       dts:  292864    type: audio
packet #:     454       dts:  517574    type: video *
packet #:     455       dts:  521327    type: video *
packet #:     456       dts:  525080    type: video *
packet #:     457       dts:  528833    type: video *
packet #:     458       dts:  532589    type: video *
packet #:     459       dts:  536342    type: video *
packet #:     460       dts:  540095    type: video *
packet #:     461       dts:  543848    type: video *
packet #:     462       dts:  293888    type: audio
packet #:     463       dts:  294912    type: audio
packet #:     464       dts:  295936    type: audio
packet #:     465       dts:  296960    type: audio
packet #:     466       dts:  297984    type: audio
packet #:     467       dts:  299008    type: audio
packet #:     468       dts:  300032    type: audio
packet #:     469       dts:  301056    type: audio
packet #:     470       dts:  302080    type: audio
packet #:     471       dts:  303104    type: audio
packet #:     472       dts:  304128    type: audio
packet #:     473       dts:  305152    type: audio
packet #:     474       dts:  306176    type: audio
packet #:     475       dts:  307200    type: audio
packet #:     476       dts:  547604    type: video *
packet #:     477       dts:  551357    type: video *
packet #:     478       dts:  555110    type: video *
packet #:     479       dts:  558863    type: video *
packet #:     480       dts:  562619    type: video *
packet #:     481       dts:  566372    type: video *
packet #:     482       dts:  570125    type: video *
packet #:     483       dts:  573878    type: video *
packet #:     484       dts:  308224    type: audio
packet #:     485       dts:  309248    type: audio
packet #:     486       dts:  310272    type: audio
packet #:     487       dts:  311296    type: audio
packet #:     488       dts:  312320    type: audio
packet #:     489       dts:  313344    type: audio
packet #:     490       dts:  314368    type: audio
packet #:     491       dts:  315392    type: audio
packet #:     492       dts:  316416    type: audio
packet #:     493       dts:  317440    type: audio
packet #:     494       dts:  318464    type: audio
packet #:     495       dts:  319488    type: audio
packet #:     496       dts:  320512    type: audio
packet #:     497       dts:  321536    type: audio
packet #:     498       dts:  577634    type: video *
packet #:     499       dts:  581387    type: video *
packet #:     500       dts:  585140    type: video *
packet #:     501       dts:  588893    type: video *
packet #:     502       dts:  592649    type: video *
packet #:     503       dts:  596402    type: video *
packet #:     504       dts:  600155    type: video *
Got video frame at time 592649

However, if I change av_seek_frame() to use stream_index = 0, I still get a seek result of 0 (indicating success) but I get the following (desired) output:

packet #:       0       dts:       0    type: audio
packet #:       1       dts:    1024    type: audio
packet #:       2       dts:    2048    type: audio
packet #:       3       dts:    3072    type: audio
packet #:       4       dts:    4096    type: audio
packet #:       5       dts:    5120    type: audio
packet #:       6       dts:    6144    type: audio
packet #:       7       dts:   -6006    type: video *
packet #:       8       dts:   -3003    type: video *
packet #:       9       dts:       0    type: video *
packet #:      10       dts:    3003    type: video *
packet #:      11       dts:    7168    type: audio
packet #:      12       dts:    8192    type: audio
packet #:      13       dts:    9216    type: audio
packet #:      14       dts:   10240    type: audio
packet #:      15       dts:   11264    type: audio
packet #:      16       dts:   12288    type: audio
packet #:      17       dts:   13312    type: audio
packet #:      18       dts:    6006    type: video *
Got video frame at time 0

ffprobe's output for the first several packets, showing that a video frame exists and how the two video packets with DTS = -6006 and -3003 are skipped:

ffprobe -show_packets SIMPSONS_D2-CallOfTheSimpsons.m4v
ffprobe version N-45279-g1a104bf Copyright (c) 2007-2012 the FFmpeg developers
  built on Oct 10 2012 19:19:16 with gcc 4.7.2 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-pthreads --enable-runtime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r --enable-libass --enable-libcelt --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libnut --enable-libopenjpeg --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libutvideo --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  libavutil      51. 74.100 / 51. 74.100
  libavcodec     54. 65.100 / 54. 65.100
  libavformat    54. 31.100 / 54. 31.100
  libavdevice    54.  3.100 / 54.  3.100
  libavfilter     3. 19.102 /  3. 19.102
  libswscale      2.  1.101 /  2.  1.101
  libswresample   0. 16.100 /  0. 16.100
  libpostproc    52.  1.100 / 52.  1.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'SIMPSONS_D2-CallOfTheSimpsons.m4v':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42isomavc1
    encoder         : HandBrake 0.9.5 2011010300
  Duration: 00:23:06.51, start: 0.000000, bitrate: 1944 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
720x480 [SAR 118:135 DAR 59:45], 1774 kb/s, 25.50 fps, 29.97 tbr, 90k
tbn, 180k tbc
    Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz,
stereo, s16, 164 kb/s
    Stream #0:2(und): Subtitle: mov_text (text / 0x74786574)
[PACKET]
codec_type=audio
stream_index=1
pts=0
pts_time=0.000000
dts=0
dts_time=0.000000
duration=1024
duration_time=0.021333
convergence_duration=N/A
convergence_duration_time=N/A
size=6
pos=168
flags=K
[/PACKET]
[PACKET]
codec_type=audio
stream_index=1
pts=1024
pts_time=0.021333
dts=1024
dts_time=0.021333
duration=1024
duration_time=0.021333
convergence_duration=N/A
convergence_duration_time=N/A
size=21
pos=174
flags=K
[/PACKET]
[PACKET]
codec_type=audio
stream_index=1
pts=2048
pts_time=0.042667
dts=2048
dts_time=0.042667
duration=1024
duration_time=0.021333
convergence_duration=N/A
convergence_duration_time=N/A
size=10
pos=195
flags=K
[/PACKET]
[PACKET]
codec_type=audio
stream_index=1
pts=3072
pts_time=0.064000
dts=3072
dts_time=0.064000
duration=1024
duration_time=0.021333
convergence_duration=N/A
convergence_duration_time=N/A
size=10
pos=205
flags=K
[/PACKET]
[PACKET]
codec_type=audio
stream_index=1
pts=4096
pts_time=0.085333
dts=4096
dts_time=0.085333
duration=1024
duration_time=0.021333
convergence_duration=N/A
convergence_duration_time=N/A
size=10
pos=215
flags=K
[/PACKET]
[PACKET]
codec_type=audio
stream_index=1
pts=5120
pts_time=0.106667
dts=5120
dts_time=0.106667
duration=1024
duration_time=0.021333
convergence_duration=N/A
convergence_duration_time=N/A
size=10
pos=225
flags=K
[/PACKET]
[PACKET]
codec_type=audio
stream_index=1
pts=6144
pts_time=0.128000
dts=6144
dts_time=0.128000
duration=1024
duration_time=0.021333
convergence_duration=N/A
convergence_duration_time=N/A
size=10
pos=235
flags=K
[/PACKET]
[PACKET]
codec_type=video
stream_index=0
pts=0
pts_time=0.000000
dts=-6006
dts_time=-0.066733
duration=N/A
duration_time=N/A
convergence_duration=N/A
convergence_duration_time=N/A
size=36509
pos=245
flags=K
[/PACKET]
[PACKET]
codec_type=video
stream_index=0
pts=3003
pts_time=0.033367
dts=-3003
dts_time=-0.033367
duration=N/A
duration_time=N/A
convergence_duration=N/A
convergence_duration_time=N/A
size=35
pos=36754
flags=_
[/PACKET]
[PACKET]
codec_type=video
stream_index=0
pts=9009
pts_time=0.100100
dts=0
dts_time=0.000000
duration=N/A
duration_time=N/A
convergence_duration=N/A
convergence_duration_time=N/A
size=32245
pos=36789
flags=_
[/PACKET]

Change History (2)

comment:1 Changed 5 years ago by cehoyos

  • Keywords seek added

comment:2 in reply to: ↑ description Changed 3 years ago by aljungberg

This bug seems to still exist as of ffmpeg 2.2. It's particularly bad when seeking to 0 and the first frame contains the first key frame. It gets dropped so when decoding finally gets going there's a bunch of grey goo of delta frames until the second key frame.

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