M4V Timecodes?

[Penumbra]

Greeting gentlepersons -

As this is my first post, I'll be brief.

In MPEG2, the GOP header clearly defines a timecode - and we can (and do) use that field to track the time a video was recorded, and carry that timecode through the workflow.

We recently purchased the MPEG-4 specification thinking that we would really like to transition to H.264 and MP4 for streaming video.

The problem we've encountered is that I can't seem to find reference anywhere in the MPEG4 specification of the MP4 container where to store the absolute time code - without which, I can not proceed.

If I recorded a piece of video at 12:34:56;00 and I want to preserve that after encoding to MP4 - how can I do that?

Am I misreading something here, oh gurus of video?

Thanks in advance,

Pen

[aedipuss]

most camcorders use a separate file to record timecodes to with h264. also the filename of the video often incorporates the start timecode.

other than those i don't think it's part of the spec. there may be unused parts of the header you could insert it in, but then that may make it unreadable by normal programs.

[Penumbra]

most camcorders use a separate file to record timecodes to with h264. also the filename of the video often incorporates the start timecode.

other than those i don't think it's part of the spec. there may be unused parts of the header you could insert it in, but then that may make it unreadable by normal programs.

I was afraid of that...

Is it just me, or does this seem like a strange thing to remove from the headers?

I work in broadcast media, and without the ability to know on a frame accurate basis what the timecode of the frame being rendered is - MP4 is useless for anything but an end-of-the-line format.

Pen

[redwudz]

Most highly compressed formats like H.264, Real, Xvid/Divx and others are 'end-of-the-line' formats. Not really meant for editing.

Also key frames are more widely spaced with those type of formats. Xvid, for example, has about 300 frames between key frames and H.264 is similar. This makes frame accurate editing very difficult.

You can convert to other formats with a program like Neoscene for frame accurate editing, but that's another step.

And welcome to our forums.

[aedipuss]

don't quote me, but i've always thought mp4(h264) was designed as an overly compressed final display format just for computers and small hand held devices. editing the crud is just painful.

[Penumbra]

Argh, I say...

That's what I was coming to realize as I pushed down this pathway, but I hoped one of you may know better.

That's too bad.

This takes me back to step 1, which is to keep the files as MPEG2-TS files, and find a way to stream them that WMP on XP supports.....

That's another topic that I'll post in the streaming forum.

Thanks guys,

Pen