Opened 13 years ago

Closed 13 years ago

#445 closed defect (fixed)

Wrong FLV duration metadata field

Reported by: burek Owned by: Michael Niedermayer
Priority: minor Component: ffmpeg
Version: git-master Keywords: flv meta duration
Cc: Blocked By:
Blocking: Reproduced by developer: yes
Analyzed by developer: no

Description

When ffmpeg is used like this:
ffmpeg -t 00:00:30 -i valid.flv -acodec copy -vcodec copy invalid.flv
(extracting a part of the video to a new file) then the resulting file (invalid.flv) contains wrong duration metadata field (copied from the original 'valid.flv') which confuses all FLV web players, because the navigation can't be accurate because of that.

I personally always use "flvmeta -Uf invalid.flv" after this kind of cutting, but it would be nice if ffmpeg would actually write correct values in the output file

Change History (3)

comment:1 by Carl Eugen Hoyos, 13 years ago

Complete, uncut output missing.

comment:2 by burek, 13 years ago

I'm not sure what output do you need, because it happens with hundreds of videos I've been working for so far. For example:

ffmpeg -f video4linux2 -i /dev/video0 -vcodec libx264 -crf 20 -threads 0 out.flv

and then

ffmpeg -ss 00:01:00 -t 00:00:25 -i out.flv -acodec copy -vcodec copy sample.flv

The file sample.flv has got an invalid metadata "duration" field.

Here is the actual example:

# ffmpeg -i final.flv
ffmpeg version git-2011-08-19-ada49f9, Copyright (c) 2000-2011 the FFmpeg developers
  built on Sep  5 2011 12:41:18 with gcc 4.6.1
  configuration: --enable-static --enable-shared --enable-gpl --enable-nonfree --enable-postproc --enable-runtime-cpudetect --enable-bzlib --enable-libfaac --enable-libopenjpeg --enable-libx264 --enable-zlib --enable-libaacplus --enable-libfaac --extra-cflags=-fPIC
  libavutil    51. 12. 0 / 51. 12. 0
  libavcodec   53. 11. 0 / 53. 11. 0
  libavformat  53.  8. 0 / 53.  8. 0
  libavdevice  53.  3. 0 / 53.  3. 0
  libavfilter   2. 32. 0 /  2. 32. 0
  libswscale    2.  0. 0 /  2.  0. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[flv @ 0x1f0c420] Estimating duration from bitrate, this may be inaccurate

Seems stream 0 codec frame rate differs from container frame rate: 50.00 (50/1) -> 50.00 (50/1)
Input #0, flv, from 'final.flv':
  Metadata:
    duration        : 21117
    width           : 320
    height          : 240
    videodatarate   : 118
    framerate       : 50
    videocodecid    : 7
    audiodatarate   : 31
    audiosamplerate : 44100
    audiosamplesize : 16
    stereo          : true
    audiocodecid    : 10
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    creation_time   : 1970-01-01 00:00:00
    encoder         : Lavf53.8.0
    filesize        : 421422299
  Duration: 05:51:57.33, start: 0.040000, bitrate: 152 kb/s
    Stream #0.0: Video: h264 (High), yuv420p, 320x240, 120 kb/s, 50 tbr, 1k tbn, 50 tbc
    Stream #0.1: Audio: aac, 44100 Hz, 2 channels (FC), s16, 32 kb/s
At least one output file must be specified

and then

# ffmpeg -ss 00:00:10 -t 00:00:30 -i final.flv -acodec copy -vcodec copy sample.flv
ffmpeg version git-2011-08-19-ada49f9, Copyright (c) 2000-2011 the FFmpeg developers
  built on Sep  5 2011 12:41:18 with gcc 4.6.1
  configuration: --enable-static --enable-shared --enable-gpl --enable-nonfree --enable-postproc --enable-runtime-cpudetect --enable-bzlib --enable-libfaac --enable-libopenjpeg --enable-libx264 --enable-zlib --enable-libaacplus --enable-libfaac --extra-cflags=-fPIC
  libavutil    51. 12. 0 / 51. 12. 0
  libavcodec   53. 11. 0 / 53. 11. 0
  libavformat  53.  8. 0 / 53.  8. 0
  libavdevice  53.  3. 0 / 53.  3. 0
  libavfilter   2. 32. 0 /  2. 32. 0
  libswscale    2.  0. 0 /  2.  0. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[flv @ 0x82f420] Estimating duration from bitrate, this may be inaccurate

Seems stream 0 codec frame rate differs from container frame rate: 50.00 (50/1) -> 50.00 (50/1)
Input #0, flv, from 'final.flv':
  Metadata:
    duration        : 21117
    width           : 320
    height          : 240
    videodatarate   : 118
    framerate       : 50
    videocodecid    : 7
    audiodatarate   : 31
    audiosamplerate : 44100
    audiosamplesize : 16
    stereo          : true
    audiocodecid    : 10
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    creation_time   : 1970-01-01 00:00:00
    encoder         : Lavf53.8.0
    filesize        : 421422299
  Duration: 05:51:57.33, start: 0.040000, bitrate: 152 kb/s
    Stream #0.0: Video: h264 (High), yuv420p, 320x240, 120 kb/s, 50 tbr, 1k tbn, 50 tbc
    Stream #0.1: Audio: aac, 44100 Hz, 2 channels (FC), s16, 32 kb/s
Output #0, flv, to 'sample.flv':
  Metadata:
    duration        : 21117
    width           : 320
    height          : 240
    videodatarate   : 118
    framerate       : 50
    videocodecid    : 7
    audiodatarate   : 31
    audiosamplerate : 44100
    audiosamplesize : 16
    stereo          : true
    audiocodecid    : 10
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    creation_time   : 1970-01-01 00:00:00
    filesize        : 421422299
    encoder         : Lavf53.8.0
    Stream #0.0: Video: libx264, yuv420p, 320x240, q=2-31, 120 kb/s, 1k tbn, 1k tbc
    Stream #0.1: Audio: libaacplus, 44100 Hz, 2 channels (FC), 32 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
Press [q] to stop, [?] for help
frame=  780 fps=  0 q=-1.0 Lsize=     629kB time=00:00:29.96 bitrate= 172.1kbits/s
video:480kB audio:122kB global headers:0kB muxing overhead 4.504534%

so, sample.flv has got wrong duration (21117 instead of 25 or 31, i guess it's just been copied from the original flv file, i.e. not calculated):

# ffmpeg -i sample.flv
ffmpeg version git-2011-08-19-ada49f9, Copyright (c) 2000-2011 the FFmpeg developers
  built on Sep  5 2011 12:41:18 with gcc 4.6.1
  configuration: --enable-static --enable-shared --enable-gpl --enable-nonfree --enable-postproc --enable-runtime-cpudetect --enable-bzlib --enable-libfaac --enable-libopenjpeg --enable-libx264 --enable-zlib --enable-libaacplus --enable-libfaac --extra-cflags=-fPIC
  libavutil    51. 12. 0 / 51. 12. 0
  libavcodec   53. 11. 0 / 53. 11. 0
  libavformat  53.  8. 0 / 53.  8. 0
  libavdevice  53.  3. 0 / 53.  3. 0
  libavfilter   2. 32. 0 /  2. 32. 0
  libswscale    2.  0. 0 /  2.  0. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[flv @ 0x65a420] Estimating duration from bitrate, this may be inaccurate
Input #0, flv, from 'sample.flv':
  Metadata:
    stereo          : true
    duration        : 21117
    width           : 320
    height          : 240
    videodatarate   : 118
    framerate       : 50
    videocodecid    : 7
    audiodatarate   : 31
    audiosamplerate : 44100
    audiosamplesize : 16
    audiocodecid    : 10
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    creation_time   : 1970-01-01 00:00:00
    encoder         : Lavf53.8.0
    filesize        : 644492
  Duration: 00:00:31.32, start: 0.024000, bitrate: 152 kb/s
    Stream #0.0: Video: h264 (High), yuv420p, 320x240, 120 kb/s, 25 tbr, 1k tbn, 50 tbc
    Stream #0.1: Audio: aac, 44100 Hz, 2 channels (FC), s16, 32 kb/s
At least one output file must be specified

comment:3 by Michael Niedermayer, 13 years ago

Reproduced by developer: set
Resolution: → fixed
Status: new → closed

locally fixed, will be pushed soon

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