[FFmpeg-soc] ALAC Benchmarks
realityman at gmx.net
Thu Aug 21 17:49:33 CEST 2008
On Thursday 21 Aug 2008 9:06:59 pm Guillaume POIRIER wrote:
> 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.
> > And please do not pay heed to the doubting hordes at Hydrogenaudio who
> > say that the encoded audio "lacks bass" and assorted nonsense :-) .
> > I'm no expert but I think you don't need any listening tests to confirm
> > if its lossless.
> That's what I thought too.
Well if you try it out, tell me how it goes!
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