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Old 30 July 2009, 06:38 pm   #7
andyslim
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Join Date: Jul 2009
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ARGH, vbulletin ate my whole post!

I'm one of the developers of SqueezeCenter and wanted to chime in here with my two cents. I think everyone, myself included, is over-reacting just a bit on this issue, and there might be a simple solution. Here is some background:

Our Squeezebox products include native decoders for PCM, AIFF, FLAC, MP3, Vorbis, and WMA. We try to support as many other formats as possible through a generic transcoding framework. This makes use of command-line apps piped together to transcode into one of the supported native formats (usually FLAC, although sometimes MP3 if bandwidth is a concern for someone). We try to use off-the-shelf 3rd party decoders for this whenever possible, it doesn't make sense for us to implement our own command-line decoder.

So we ship these command-line decoders for out-of-the-box support for transcoding to FLAC: alac, faad, flac, mppdec, sox (for downsampling), and wvunpack. We don't ship LAME for licensing reasons, but users can install it manually for transcoding to MP3.

MPC transcoding is defined via the following rules:

Code:
mpc pcm * *
	# IR
	[mppdec] --raw-le --silent --prev --gain 2 - -

mpc aif * *
	# IR
	[mppdec] --raw-be --silent --prev --gain 2 - -

mpc flc * *
	# IR
	[mppdec] --silent --prev --gain 2 - - | [flac] -cs --totally-silent --compression-level-0 -

mpc mp3 * *
	# IRB:{BITRATE=-B %B}D:{RESAMPLE=--resample %D}
	[mppdec] --silent --prev --gain 3 - - | [lame] --silent -q $QUALITY$ $RESAMPLE$ -v $BITRATE$ - -
So here, we send mppdec data on stdin and expect wav/pcm/aiff back on stdout piped to the transcoder, or to send directly to the device. PCM/AIFF is used to support our 1st-gen Squeezebox that doesn't support FLAC.

With mpcdec, I believe the only features we are missing are raw PCM/AIFF output (--raw-le/--raw-be). As far as I can tell, we don't need --prev or --gain anymore, as the next version of SC will support reading the MPC RG headers (from both SV7 and SV8) and apply those directly using our standard firmware-based RG system.

We could disable MPC->PCM/AIFF support, but that would leave our older products having to use MP3 for transcoding.

So do you think it would be easy to add raw output support to mpcdec?
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