[vlc-devel] The speed of transcoding is slow

[Juha Jeronen]

Hi,

On 04/15/2011 06:57 AM, zhu shi song wrote:
> Dear lists, 
>    I have AVI video file and hope to transcode it to MP4(H.264+AAC).  VLC works well, but the speed of transcoding is the same long as playing, so it's very slow.  If the video have 10 minutes long, it will cost the same time transcoding.  The waiting is very tedious.  I have got one H.264 to AVI tool, for 10 minutes long video file, the tool just costs about 1 minute  completing to transcode.  

What are the video and audio formats the H.264 to AVI tool is producing?
Since AVI is just a container, it may contain different formats. If the
tool is just copying the encoded video and audio as-is into the new
container (or e.g. re-encoding only the audio), it'll naturally be
faster than actually transcoding everything.

Also, if the output format of the video that is written into the AVI is
an older one (e.g. XviD), it'll encode (probably much) faster than
H.264. If you meant AVI to H.264 (and the tool is converting from AVI to
MP4), then disregard the above.

A similar comment applies to the AVI to MP4 conversion, if the original
data in the AVI is already H.264+AAC. In that case, a minimal conversion
into MP4 would only require a change of the container. I don't know if
VLC detects this. It probably does exactly what it's told to ;)

Changing the encoding options might help making VLC faster, as Kaarlo
suggested.

Checking which codecs were used in the input file (to know whether there
is a need to actually transcode) might also help.

Hope this helps,

 -J