Opened 3 years ago

Last modified 3 years ago

#5213 open enhancement

Change Flags for MPEG files without reencode

Reported by: mboufleur Owned by:
Priority: wish Component: avcodec
Version: git-master Keywords: mpeg2video aspect
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no

Description

Is it possible to implemente a feature in MPEG to change flags in MPEG files, without the need to reencode? This would greatly help in cases when it is needed to change aspect ratio, frame rate, encoding profiles, etc.

Change History (3)

comment:1 Changed 3 years ago by cehoyos

Please make this ticket more specific: For what kind of file would you like to change which property?
I believe such a request is valid (and for some formats, this may not be too difficult) but please note that no such bitstream filter exists yet.

comment:2 Changed 3 years ago by mboufleur

I believe this would be particularly useful for MPEG-1 and MPEG-2 videos, regardless if they are within MPEG-PS, Transport Stream, RAW Mpeg Video, Quicktime MOV, MXF, etc.

The changes would happen at the video headers, and there would be some input info from the user side to specify which parameter to change, and also the value (aspect ratio, frame rate, bitrate, timestamp, etc). I believe these sort of changes could be done with a hex editor, but I lack the inner depths of MPEG encode to confirm that.

There are some applications that do exactly that (DVD Patcher, Restream, Womble MPEG Video Wizard, TMPGEnc MPEG Editor, TMPGEnc Smart Renderer, etc), but almost all of them are Windows oriented, and depending on the application you may get specific features and/or limitations.

There are also other tools mainly targeted at DVD packages, that perform changes at the IFO level, but that is not what this request is for.

comment:3 Changed 3 years ago by cehoyos

  • Component changed from undetermined to avcodec
  • Keywords mpeg2video aspect added
  • Priority changed from normal to wish
  • Status changed from new to open
  • Version changed from unspecified to git-master

Afaict, this is a valid feature request for aspect ratio change in mpeg1video and mpeg2video.

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