Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.


Go Back   Doom9's Forum > Video Encoding > MPEG-4 AVC / H.264

Thread Tools Search this Thread Display Modes
Old 5th March 2021, 08:27   #1  |  Link
Registered User
Join Date: Feb 2021
Posts: 1
QTFF, ISO 14496-12 and elst-media_time value

1. What is the priority standard for decoding mov files?
2. What value should be set in elst/media_time? Can we check it somehow?
  • In QuickTime File Format Specification media_time is DT value:
    The edit list atom provides the initial DT value if it is nonempty (nonzero).
  • In ISO IEC 14496-12 media_time is CT value.
    The Edit List Box provides the initial CT value if it is non‐empty (non‐zero).
It looks like the media_time value can be calculated and checked with ct + ctts (for ISO IEC 14496-12). But how to interpret the next note?
Edits are not restricted to fall on sample times. This means that when entering an edit, it can be necessary to (a) back up to a sync point, and pre‐roll from there and then (b) be careful about the duration of the first sample it might have been truncated if the edit enters it during its normal duration. If this is audio, that frame might need to be decoded, and then the final slicing done. Likewise, the duration of the last sample in an edit might need slicing.
Does this mean that the media_time may not indicate a specific PTS of the first frame but in the "middle" of two frames for example? But I did not find in the standard how to work with this situation and which of these two frames must be displayed in such a situation as the first frame.
aymv is offline   Reply With Quote

mov, quicktime

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT +1. The time now is 01:29.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.