[MEncoder-users] converting and subtitle questions

[zechao wang]

Hello Erik Slagter: 

I want to convert rmvb files to mp4 for my cellphone.

mencoder my.rmvb -ovc lavc -oac mp3lame -o my.avi

ffmpeg -y -i my.avi -vcodec xvid -s 400x240 -r 29.97 -b 600 -acodec aac -ac 2 -ar 48000 -ab 128 -vol 200 -f mp4 my.mp4

With above commands, it can works well. But the quality is not good, especially when playing the dark frames, there are too much mosaic.

If you are familiar with ffmepg, how should i do if i want to get the high-quailty mp4 file ? Please give me some advice, thanks you very much.


Erik Slagter <erik at slagter.name> 写道： Alex Samad wrote:

> I was under the understanding that using mencoder to produce an avi and
> then using MP4Box to extract the video + audio and then remuxing would
> be the same as ffmpeg ? (I have used mencoder for a while and am getting
> used to using it) but what you seem to be saying its that it would be
> better to encode with ffmpeg directly.

If I were in a situation where I could choose between mplayer/avi+mp4box 
and ffmpeg (i.e. no filtering and no subtitles), I'd definitely choose 
for ffmpeg. FFmpeg has most codecs and formats native, and keeping all 
frames within one application imho gives less chance to a/v desync; it 
can maintain the original timestamps with the frames. FFmpeg also has 
some options to force a/v sync where it doesn't come naturally ;-) (i.e. 
the timestamps are wrong).

Using avi as intermediate file will probably work, but is prone to 
problems (especially if the input is an mpeg stream with b frames) as 
avi has a very different way of representing "timestamps" than the 
various types of mpeg streams.
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