Time-stretch without re-encoding

[varunb]

Is it possible to change the time or length if an audio file without re-encoding it....for example i need to convert the frame rate of an AC3 or DTS file, basically from 23.976 to 25.000, without encoding it to some other format. Is it possible ?

[check]

mkv can handle that.

[varunb]

but how do i do it ? Can u be a bit more specific pls as i hav never done any encoding in mkv format before.

[check]

have a look at mkvmerge. mkv is a container, not a codec, you don't need to re-encode

[tebasuna51]

When we need change the audio duration to match the video duration in other standard fps, is for standalone player compatibility. To play in PC we don't need change to a different fps.

The matroska container (.mkv) can't be played in standard standalone player, then can't be a solution to the problem.

To timestretch a dts or ac3 we need always re-encode.

[miztadux]

On the other hand, for example with divx/xvid video, you can easily change the FPS of the movie without re-encoding it.
And since 23.976 is better for movies (25 fps introduces a 4% speed up // original, whereas 23.976 only 0.1%) it can be a viable solution if you don't need PAL material.

[tebasuna51]

On the other hand, for example with divx/xvid video, you can easily change the FPS of the movie without re-encoding it.
And since 23.976 is better for movies (25 fps introduces a 4% speed up // original, whereas 23.976 only 0.1%) it can be a viable solution if you don't need PAL material.
Yep, the problem is only if PAL material is needed to be played for standalone+TV without NTSC support.

Without re-encode there are a solution with VirtualDub -> Video -> Frame Rate...-> Frame Rate Conversion -> Convert to fps: 25
The video is not re-encoded but a duplicate video frame is inserted every 23.414 original frames then the video duration is identical (at 25 f/s) than the audio without modification.