[FFmpeg-trac] #7334(ffmpeg:new): ffmpeg demux into audio and video resets PTS
FFmpeg
trac at avcodec.org
Mon Jul 30 03:37:16 EEST 2018
#7334: ffmpeg demux into audio and video resets PTS
-------------------------------------+-------------------------------------
Reporter: mukunm | Type: defect
Status: new | Priority: normal
Component: ffmpeg | Version: git-
Keywords: ffmpeg, | master
demux | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
**Demuxing**
I am demuxing TS segments into audio and video as follows.
`ffmpeg -y -i input.ts -vcodec copy -an output_video.ts`
`ffmpeg -y -i input.ts -acodec copy -vn output_audio.aac`
**Inspecting Input**
The `start_pts` and `start_time` on `input.ts` are as shown below. I was
able to inspect these values using `ffprobe -show_streams -print_format
json input.ts`
`"start_pts": 8306558438,`
`"start_time": "92295.093756",`
**Inspecting output video**
The output .ts has some default `start_pts` and `start_time` values as
shown below. These were also obtained using the same `ffprobe` command as
indicated above.
`"start_pts": 126000,`
`"start_time": "1.400000",`
**Inspecting output audio**
The same `ffprobe` command on `output_audio.aac` shows that the output aac
has invalid `codec_tag` and `codec_tag_string` as shown below. The
`start_pts` and `start_time` are not present in the `output_audio.aac`.
`"codec_tag_string": "[0][0][0][0]", (should have been [15][0][0][0])`
`"codec_tag": "0x0000", (should have been 0xf000)`
**Questions**
1. Wondering if this difference in the `start_pts`, `start_time`,
`codec_tag` is expected?
2. If it is expected, what can I do to ensure that the all of these
parameters get retained on the output?
3. If it is not expected, is there some more information I can share to
track this down?
''Note''
''There were other outputs that I found inconsistent in the `ffprobe`
command for the `output_audio.aac` like `duration etc.`. I shared what I
thought are most valuable at this point. If required I can share complete
outputs from all of the above executions.''
ffmpeg version used:
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Ticket URL: <https://trac.ffmpeg.org/ticket/7334>
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