h264 parser emits every other video packet without pts for mbaff/paff inputs

[Aman]

Expected:

Feeding h264 video into lavf would produce AVPackets with pts set.

Actual:

On some inputs (which are mbaff/paff), only every other AVPacket has pts set.

How to reproduce:

$ ffprobe -select_streams v -show_packets -print_format json http://tmm1.s3.amazonaws.com/uk-nopts.mpg

ffprobe version N-90375-ge5b4cd4c4a Copyright (c) 2007-2018 the FFmpeg developers
  built with Apple LLVM version 9.0.0 (clang-900.0.39.2)
  configuration: --prefix=/tmp/ffmpeg-master --enable-libxml2 --enable-shared --disable-static --disable-stripping --disable-manpages
  libavutil      56. 11.100 / 56. 11.100
  libavcodec     58. 14.100 / 58. 14.100
  libavformat    58. 10.100 / 58. 10.100
  libavdevice    58.  2.100 / 58.  2.100
  libavfilter     7. 13.100 /  7. 13.100
  libswscale      5.  0.102 /  5.  0.102
  libswresample   3.  0.101 /  3.  0.101

Input #0, mpegts, from 'http://tmm1.s3.amazonaws.com/uk-nopts.mpg':
  Duration: 00:00:21.66, start: 2500.739878, bitrate: 5809 kb/s
  Program 17664
    Stream #0:0[0x12d]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x12e](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
    Stream #0:2[0x132](eng): Unknown: none ([17][0][0][0] / 0x0011) (visual impaired) (dependent)
    Stream #0:3[0x131](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
Unsupported codec with id 0 for input stream 2
{
    "packets": [
        {
            "codec_type": "video",
            "stream_index": 0,
            "pts": 225158417,
            "pts_time": "2501.760189",
            "dts": 225147617,
            "dts_time": "2501.640189",
            "duration": 1800,
            "duration_time": "0.020000",
            "size": "30176",
            "pos": "6016",
            "flags": "__",
            "side_data_list": [
                {
                    "side_data_type": "MPEGTS Stream ID"
                }
            ]
        },
        {
            "codec_type": "video",
            "stream_index": 0,
            "duration": 1800,
            "duration_time": "0.020000",
            "size": "11828",
            "flags": "__",
            "side_data_list": [
                {
                    "side_data_type": "MPEGTS Stream ID"
                }
            ]
        },
        {
            "codec_type": "video",
            "stream_index": 0,
            "pts": 225154817,
            "pts_time": "2501.720189",
            "dts": 225151217,
            "dts_time": "2501.680189",
            "duration": 1800,
            "duration_time": "0.020000",
            "size": "8334",
            "pos": "50008",
            "flags": "__"
        },
        {
            "codec_type": "video",
            "stream_index": 0,
            "duration": 1800,
            "duration_time": "0.020000",
            "size": "7151",
            "flags": "__",
            "side_data_list": [
                {
                    "side_data_type": "MPEGTS Stream ID"
                }
            ]
        },
        {
            "codec_type": "video",
            "stream_index": 0,
            "pts": 225162017,
            "pts_time": "2501.800189",
            "dts": 225154817,
            "dts_time": "2501.720189",
            "duration": 1800,
            "duration_time": "0.020000",
            "size": "10301",
            "pos": "66364",
            "flags": "__"
q        },
        {
            "codec_type": "video",
            "stream_index": 0,
            "duration": 1800,
            "duration_time": "0.020000",
            "size": "7819",
            "flags": "__",
            "side_data_list": [
                {
                    "side_data_type": "MPEGTS Stream ID"
                }
            ]
        },
        {
            "codec_type": "video",
            "stream_index": 0,
            "pts": 225194417,
            "pts_time": "2502.160189",
            "dts": 225158417,
            "dts_time": "2501.760189",
            "duration": 1800,
            "duration_time": "0.020000",
            "size": "93387",
            "pos": "85540",
            "flags": "__"
        },
        {
            "codec_type": "video",
            "stream_index": 0,
            "duration": 1800,
            "duration_time": "0.020000",
            "size": "23562",
            "flags": "__",
            "side_data_list": [
                {
                    "side_data_type": "MPEGTS Stream ID"
                }
            ]
        },
        ...

[mkver]

This is essentially a duplicate of #6903.

[Aman]

I discovered that I can fix the ffprobe output by telling the mpegts demuxer not to parse H264 streams:

diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
index 76d5bbb920..5fca4e822a 100644
--- a/libavformat/mpegts.c
+++ b/libavformat/mpegts.c
@@ -894,6 +894,9 @@ static int mpegts_set_stream_info(AVStream *st, PESContext *pes,
         st->codecpar->codec_id   = AV_CODEC_ID_BIN_DATA;
         st->request_probe = AVPROBE_SCORE_STREAM_RETRY / 5;
     }
+    if (st->codecpar->codec_id == AV_CODEC_ID_H264) {
+        st->need_parsing = AVSTREAM_PARSE_HEADERS;
+    }

     /* queue a context update if properties changed */
     if (old_codec_type != st->codecpar->codec_type ||

However, then there are problems decoding the video for some reason.

[Carl Eugen Hoyos]

Replying to mkver:

This is essentially a duplicate of #6903.

And several other tickets iirc.