How to use SOX to downsample > 24/96 on Touch when streaming FLAC as PCM?

[MrRalph]

I have the server stream FLAC as PCM to my Touch. The Touch cannot handle 24/176 and 24/192. How can I have SOX downsample 24/176 -> 24/88 and 24/192 -> 24/96 in such situation?

[th00ht]

I believe this is done automatically (?). Currently I'm playing 24/96 material on my beloved Squeezebox (classic) which aledgedly only handles upto 24/88. The command that is running on my SBS is:

/opt/squeezebox-server/Bin/i386-linux/sox -q -t wav - -t flac -C 0 -r 48000 -

so I assume it does a down sample to 48k.

What is a bit puzzling is that when I monitor the coaxial out, my Denon DAT recorder seems to receive a 44.1k stream; it could handle 48k. Yet the music plays fine, although there is a barely audible tremelo.

[Phil Leigh]

The Touch and SB3 are different.

On the Touch, if you stream FLAC as FLAC, all sample rates are handled automatically (176.4 and 192 are downsamples to 88.2/96 via SOX)

If you stream FLAC as PCM, 176.4 and 192 will not play, as SOX is not invoked by the standard Convert.conf entry. You will get an "unsupported file type" error message on the Touch screen.

A special entry for custom_convert.conf needs to be crafted that will convert the FLAC to PCM and downsample. This entry is only used if the sample rate is > 96.

I don't know if SBS supports the smart detection of switching to sample rate transcoding for FLAC streamed as PCM. It looks like it might work...

I've hacked around a bit and never quite managed to get this to work...


This is the entry for FLAC streamed as PCM:

flc pcm * *
# FT:{START=--skip=%t}U:{END=--until=%v}
[flac] -dcs --force-raw-format --endian=little --sign=signed $START$ $END$ -- $FILE$


This is the entry for FLAC-FLAC downsampling:

flc flc transcode *
# FT:{START=--skip=%t}U:{END=--until=%v}D:{RESAMPLE=-r %d}
[flac] -dcs $START$ $END$ -- $FILE$ | [sox] -q -t wav - -t flac -C 0 $RESAMPLE$ -

[justpassinthru]

The Touch and SB3 are different.

On the Touch, if you stream FLAC as FLAC, all sample rates are handled automatically (176.4 and 192 are downsamples to 88.2/96 via SOX)

If you stream FLAC as PCM, 176.4 and 192 will not play, as SOX is not invoked by the standard Convert.conf entry. You will get an "unsupported file type" error message on the Touch screen.

A special entry for custom_convert.conf needs to be crafted that will convert the FLAC to PCM and downsample. This entry is only used if the sample rate is > 96.

I don't know if SBS supports the smart detection of switching to sample rate transcoding for FLAC streamed as PCM. It looks like it might work...

I've hacked around a bit and never quite managed to get this to work...


This is the entry for FLAC streamed as PCM:

flc pcm * *
# FT:{START=--skip=%t}U:{END=--until=%v}
[flac] -dcs --force-raw-format --endian=little --sign=signed $START$ $END$ -- $FILE$


This is the entry for FLAC-FLAC downsampling:

flc flc transcode *
# FT:{START=--skip=%t}U:{END=--until=%v}D:{RESAMPLE=-r %d}
[flac] -dcs $START$ $END$ -- $FILE$ | [sox] -q -t wav - -t flac -C 0 $RESAMPLE$ -

Phil,

I am not quite clear on what you suggest to get the Touch to auto down convert from 176.4/24 to 88.2/24. Should the custom_convert.conf file only contain the FLC to FLC transcode statement? Or is ir to be a copy of the covert.conf, with the the FLC to PCM statement be commented out?

Thanks for your help.

[Phil Leigh]

Phil,

I am not quite clear on what you suggest to get the Touch to auto down convert from 176.4/24 to 88.2/24. Should the custom_convert.conf file only contain the FLC to FLC transcode statement? Or is ir to be a copy of the covert.conf, with the the FLC to PCM statement be commented out?

Thanks for your help.

OK - basically whatever you put in custom_convert.conf will override the matching entry or entries in convert.conf

So if you ONLY want to change the way 176.4 or 192 FLAC files are handled on a Touch (or transporter) you would just need to have a flc flc transcode * entry in custom_convert.conf

SBS will do everything automatically for flac file streaming - you do not need to change anything.

If you want to stream flac files as PCM with auto down-sampling of 176.4 and 192... someone else will have to jump in and help - I've never managed to get this to work, although I am 100% positive it can be made to work.

[justpassinthru]

OK - basically whatever you put in custom_convert.conf will override the matching entry or entries in convert.conf

So if you ONLY want to change the way 176.4 or 192 FLAC files are handled on a Touch (or transporter) you would just need to have a flc flc transcode * entry in custom_convert.conf

SBS will do everything automatically for flac file streaming - you do not need to change anything.

If you want to stream flac files as PCM with auto down-sampling of 176.4 and 192... someone else will have to jump in and help - I've never managed to get this to work, although I am 100% positive it can be made to work.

Phil,
Thanks so much for your prompt response. I have been perusing your other posts and now find myself even more confused. I purchased some 176.4/24 files to burn to DVD to see how much better they might sound. (They also play fine on my PC via Media Monkey from my NAS; I am using a ReadyNAS Duo as my media server.) I then decided to try and see if my Touch would play them. I got the "unsupported format" msg instead and hence began my forum search. While reading your other posts I came across this statement -

"The Touch CAN output 88.2 in the following circumstances:
1) you are playing a 176.4 file - it will be downsampled by SOX to 88.2 assuming you haven't fiddled with the FLAC Transcode entry in convert.conf"

That is all I need to happen. I am not sure why the the Touch did not downsample to 88.2/24 automatically given that I had not edited the convert.conf file in any manner. Does this statement infer that the Squeeze Server must be running on the PC and using SOX and that the downsample will not work when running Squeeze Server (full version) from a ReadyNAS Media server?

Thanks again for your help.

[Phil Leigh]

Phil,
Thanks so much for your prompt response. I have been perusing your other posts and now find myself even more confused. I purchased some 176.4/24 files to burn to DVD to see how much better they might sound. (They also play fine on my PC via Media Monkey from my NAS; I am using a ReadyNAS Duo as my media server.) I then decided to try and see if my Touch would play them. I got the "unsupported format" msg instead and hence began my forum search. While reading your other posts I came across this statement -

"The Touch CAN output 88.2 in the following circumstances:
1) you are playing a 176.4 file - it will be downsampled by SOX to 88.2 assuming you haven't fiddled with the FLAC Transcode entry in convert.conf"

That is all I need to happen. I am not sure why the the Touch did not downsample to 88.2/24 automatically given that I had not edited the convert.conf file in any manner. Does this statement infer that the Squeeze Server must be running on the PC and using SOX and that the downsample will not work when running Squeeze Server (full version) from a ReadyNAS Media server?

Thanks again for your help.

yes - this will only work if the computer running SBS is capable of running SOX... I don't think the ReadyNAS can do this.

[justpassinthru]

yes - this will only work if the computer running SBS is capable of running SOX... I don't think the ReadyNAS can do this.

The for clarifying this. I appreciate it.