[FFmpeg-soc] ALAC Benchmarks

[Jai Menon]

Hi,

On Thursday 21 Aug 2008 9:19:33 pm Jai Menon wrote:
> Hi,
>
> On Thursday 21 Aug 2008 9:06:59 pm Guillaume POIRIER wrote:
> > Hello,
> >
> > On Wed, Aug 20, 2008 at 6:52 PM, Jai Menon <realityman at gmx.net> wrote:
> > > On Wednesday 20 Aug 2008 9:33:25 pm Guillaume POIRIER wrote:
> > >> I have a question about your ALAC encoder: since this is a lossless
> > >> compression, is it safe to assume that no listening test is needed to
> > >> compare your encoder to other encoders?
> > >>
> > >> Guillaume
> > >
> > > Yes. The decoded output is bitexact to the original source. You could
> > > do ABX tests to convince yourself though :-)
> >
> > Ok. Would your mind giving me a sample commandline to compress a WAV
> > to ALAC? I imagine that there are several options that control your
> > ALAC encoder that need to be tried out?
>
> There are options to select min and max prediction orders but till I finish
> tuning the encoder completely, you could try something like :
>
> ./ffmpeg -i <file.wav> -acodec alac <output.m4a>
>
> That should give you pretty decent compression.
>
> > Is it necessary to use MP4 container to store ALAC audio?
>
> If you want the encoded alac stream to playback on an ipod, then you should
> mux into mp4(m4a). The alac stream in a mov container is iirc not
> acceptable to the ipod. Both work on itunes though.
>

Also, a quick addition. The comment regarding ipod support is based on inputs 
from Ramiro and a few others who actually own an ipod. I don't have one so I 
won't be able to confirm. It should work to the best of my knowledge...

Regards,

Jai Menon