[MPlayer-users] Fwd: FFplay ffmpeg difference in decoding?

evert vorster evorster at gmail.com
Mon Aug 25 01:19:28 CEST 2008

Hi there. Thanks for the reply.

I think this is a bug in ffmpeg, and I just wanted to report it somewhere.

All other video formats are converted preserving time. What I am
trying to say is that the video before converting and after converting
should play at the same rate, and does for very other format.

I have converted a few videos with ffmpeg, and that is why this
behaviour on .mts files seems strange. Normally, a video that lasts
for 10 seconds before conversion lasts for ten seconds after
conversion. When converting a .mts file, it suddenly lasts 20 seconds,
while the sound still lasts 10 seconds.

Futhermore, -r does not seem to have any effect on the input file on
conversion with ffmpeg, which could mean that the framerate for mts (
avchd ) files are hard-coded, which is slightly naughty. I am not a
video codec guru, though, so this is only a guess.

I do realise that avchd is a very new format, and am quite impressed
that we are able to work with it at all.
I would love to give the developers a short movie clip captured with
my canon hf100 ( vixia ) camera, if they do not have it already, so
that they have a bit more info on Canon's take on the avchd format,
which would translate in better support for the format in general for
everybody. I hope. :)

Thank you again for the workaround, I'll try and convert my videos
with Mencoder.
However, ffmpeg has the -r command which is supposed to address this
very problem, but it does not seem to work in the case of .mts files
recorded with my camcorder.

Kind regards,
-Evert Vorster-

On Sun, Aug 24, 2008 at 8:32 AM, belcampo <belcampo at zonnet.nl> wrote:
> evert vorster wrote:
>> When playing back a .mts files created by my Canon HD camcorder with
>> ffplay, they plays perfectly. Correct playback speed & sound. I think
>> the file format is AVCHD.
>> However, when I do any sort of conversion with ffmpeg, the resulting
>> video plays at half speed, and the sound playing at normal speed in
>> the encoded video. I have tried forcing the input ramerate with the -r
>> switch, which does not seem to affect the output video.
> You'll find these problems and solutions on ffmpeg users list. Mencoder
> has options like -fps 60000/1001 -ofps 30000/1001 to solve this problem.
>> Is there anywhere where I can drop a sample of this file for someone
>> to double-check? It will be smallish. :) ( 4-6 mb )
>> -Evert-
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