search

nu774 / mp4fpsmod

mp4 time code editor
http://sites.google.com/site/qaacpage/
Other
105 stars 20 forks source link

Feature Request: AAC track timecode extraction #16

Open flyser opened 9 years ago

flyser commented 9 years ago

It would be useful if mp4fpsmod could also extract the timecodes of an aac track. Currently I am remuxing video files to mkv and then use mkvextract just to delete the mkv file again. mp4fpsmod looked promising, but it seems it extracts the h264 timecodes only, right?

nu774 commented 9 years ago

it seems it extracts the h264 timecodes only, right?

Strictly speaking, mp4fpsmod works only on the first video track. I don't understand how timecode for audio track is useful and interesting, though. Isn't it just constantly increasing depending on the sample rate? If you rewrite timecode of audio track (stts time_delta), I guess many of players will just ignore it.

flyser commented 9 years ago

I dont know much about the details, but I have some video files that loose a/v sync after some time if I demux and remux them without the timecode file

nu774 commented 9 years ago

Technically, you can always achieve A/V sync by editing video timecode only, right? If your audio is too fast, you can either slow down the audio or speed up the video to keep audio and video in sync.

Since speed of audio is usually determined by the sample rate, modifying timecode of audio is not a good idea (it involves resampling or special time-stretching technique), and can be ignored by the player anyway.

nu774 commented 9 years ago

If you really, really want to edit timecode of the audio track, then I think timelineeditor of L-SMASH will do. They don't provide official win32 binaries, but you can download them here.