Opened 5 months ago

Closed 5 months ago

Last modified 5 months ago

#7334 closed defect (invalid)

ffmpeg demux into audio and video resets PTS

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

Description

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:

Change History (2)

comment:1 Changed 5 months ago by mukunm

  • Resolution set to invalid
  • Status changed from new to closed

This is not an issue.
This is expected behavior.

Found my answer here
https://stackoverflow.com/questions/51585661/ffmpeg-demux-into-audio-and-video-resets-pts

comment:2 Changed 5 months ago by cehoyos

  • Component changed from ffmpeg to undetermined
  • Keywords ffmpeg demux removed
Note: See TracTickets for help on using tickets.