transcoder order

[Ron F.]

As Philippe has outlined this is due to Spotty using a custom file type.
That said: native Ogg playback unfortunately will be removed again. The
change Philippe sponsored hasn't been accepted upstreams, and
maintaining it in my code is beyond me.

I'll look into Philippe's pull request anyway.

--

Michael

I see that in Spotty 4.4.6, that native Ogg playback has been removed. I have not been having a problem with native playback on my devices, playing many long classical music pieces without difficulty; I un-commented the custom convert rule for spt->ogg so I can continue using native playback, and see what happens.

Is there a place where I can drop custom convert rules that will be used by Spotty, but won't disturb the installed plugin?

[mherger]

> Is there a place where I can drop custom convert rules that will be used
> by Spotty, but won't disturb the installed plugin?

I'm not sure whether there's a well defined order in which those entries
are used. But I believe you should be able to put a file in the prefs
folder. Not sure, though.

--

Michael

[slartibartfast]

I see that in Spotty 4.4.6, that native Ogg playback has been removed. I have not been having a problem with native playback on my devices, playing many long classical music pieces without difficulty; I un-commented the custom convert rule for spt->ogg so I can continue using native playback, and see what happens.

Is there a place where I can drop custom convert rules that will be used by Spotty, but won't disturb the installed plugin?

Why not just use the default transcoding to FLAC?

Sent from my Pixel 3a using Tapatalk

[Ron F.]

Why not just use the default transcoding to FLAC?

Sent from my Pixel 3a using Tapatalk

Certainly transcoding from Ogg to FLAC should not result in any loss of quality, but it seems to me, that if Spotify is streaming Ogg and the renderer can render Ogg, it ought to be possible to conduct/pass the stream from originator to renderer without any intermediate transcoding!

There might be another issue here, and this might just be rumor/myth, but I have read that Spotify can stream both 44.1 and 48 KHz sample rate content in it's 320 kbps stream. I note that when Spotty transcodes to FLAC, it is always going to encode at 44.1 KHz sample rate / 16 bits. If true, and even if down-sampling some content doesn't matter, I would prefer to just pass-through to the renderer if possible.

Maybe the spt->flac convert rule can be modified so that the flac encoder can inherit the sample rate & bit depth from the decoder being used, but I don't know how to modify the existing rule to do that.

[slartibartfast]

Certainly transcoding from Ogg to FLAC should not result in any loss of quality, but it seems to me, that if Spotify is streaming Ogg and the renderer can render Ogg, it ought to be possible to conduct/pass the stream from originator to renderer without any intermediate transcoding!

There might be another issue here, and this might just be rumor/myth, but I have read that Spotify can stream both 44.1 and 48 KHz sample rate content in it's 320 kbps stream. I note that when Spotty transcodes to FLAC, it is always going to encode at 44.1 KHz sample rate / 16 bits. If true, and even if down-sampling some content doesn't matter, I would prefer to just pass-through to the renderer if possible.

Maybe the spt->flac convert rule can be modified so that the flac encoder can inherit the sample rate & bit depth from the decoder being used, but I don't know how to modify the existing rule to do that.

Hmm it seems odd that the spt to FLAC transcoding is fixed at 44.1kHz when the spt to PCM isn't as far as I can see. I wonder why that is.

Sent from my Pixel 3a using Tapatalk

[Ron F.]

Hmm it seems odd that the spt to FLAC transcoding is fixed at 44.1kHz when the spt to PCM isn't as far as I can see. I wonder why that is.

Sent from my Pixel 3a using Tapatalk

I don't know, Michael or Philippe can probably explain this. In fact, comparing to how FLAC encoding is typically done in the regular convert.conf file, I don't understand why spt->flac has to be any different.

After the Spotify Ogg stream has been decoded, why can't the FLAC encoding be done as such:
[flac] -cs --totally-silent --compression-level-0 --ignore-chunk-sizes -

[philippe_44]

> Is there a place where I can drop custom convert rules that will be used
> by Spotty, but won't disturb the installed plugin?

I'm not sure whether there's a well defined order in which those entries
are used. But I believe you should be able to put a file in the prefs
folder. Not sure, though.

--

Michael

The order of precedence of rules if the following: 1)plugins' custom-convert.conf, 2)slimserver-convert.conf, 3)custom-convert.conf, 4)convert.conf.

After 8.0, multiple rules can exist for the same tuplet (<in>-<out>-<client-type>-<client-id>) to allow different transcode logic for different inputs (stdin, remote, file) but they are reviewed in the order described above so if they do exactly the same thing, then the precedence applies.

So, to the previous question, unfortunately, AFAIK, the plugin rule rules

[philippe_44]

I don't know, Michael or Philippe can probably explain this. In fact, comparing to how FLAC encoding is typically done in the regular convert.conf file, I don't understand why spt->flac has to be any different.

After the Spotify Ogg stream has been decoded, why can't the FLAC encoding be done as such:
[flac] -cs --totally-silent --compression-level-0 --ignore-chunk-sizes -

Because what is sent to the flac encoder is raw data, so it does not know how to interpret it and needs a bit of help. When spt-pcm is used, LMS tells the player what are sample rate/ size & channels.

Now, the good news is that with the latest PR in 8.1, Michael, we know now the source sample rate, size & channels as we needed that for smart transcode

flc flc transcode *
	# IFT:{START=--skip=%t}U:{END=--until=%v}D:{RESAMPLE=-r %d}E:{NOSTART=I}
	[flac] -dcs $START$ $END$ --force-raw-format --sign=signed --endian=little -- $FILE$ | [sox] -q -t raw --encoding signed-integer -b $SAMPLESIZE$ -r $SAMPLERATE$ -c $CHANNELS$ -L - -t flac $RESAMPLE$ -C 0  -

So we could improve the spt-flc rule, I think, with (to be tested)

spt flc * *
	# RT:{START=--start-position %s}
	[spotty] -n Squeezebox -c "$CACHE$" --single-track $URL$ --bitrate 320 --disable-discovery --disable-audio-cache $START$ | [flac] -cs --channels=$CHANNELS$ --sample-rate=$SAMPLERATE$ --bps=$SAMPLESIZE$ --endian=little --sign=signed --fast --totally-silent --ignore-chunk-sizes -

[philippe_44]

I see that in Spotty 4.4.6, that native Ogg playback has been removed. I have not been having a problem with native playback on my devices, playing many long classical music pieces without difficulty; I un-commented the custom convert rule for spt->ogg so I can continue using native playback, and see what happens.

Is there a place where I can drop custom convert rules that will be used by Spotty, but won't disturb the installed plugin?

I'm trying to work on that to have the librespot maintainer include that option natively so that Michael does not have too much backporting to do, but that's my first steps with Rust and oh boy, what a nightmare

[Ron F.]

Because what is sent to the flac encoder is raw data, so it does not know how to interpret it and needs a bit of help. When spt-pcm is used, LMS tells the player what are sample rate/ size & channels.

Now, the good news is that with the latest PR in 8.1, Michael, we know now the source sample rate, size & channels as we needed that for smart transcode

flc flc transcode *
    # IFT:{START=--skip=%t}U:{END=--until=%v}D:{RESAMPLE=-r %d}E:{NOSTART=I}
    [flac] -dcs $START$ $END$ --force-raw-format --sign=signed --endian=little -- $FILE$ | [sox] -q -t raw --encoding signed-integer -b $SAMPLESIZE$ -r $SAMPLERATE$ -c $CHANNELS$ -L - -t flac $RESAMPLE$ -C 0  -

So we could improve the spt-flc rule, I think, with (to be tested)

spt flc * *
    # RT:{START=--start-position %s}
    [spotty] -n Squeezebox -c "$CACHE$" --single-track $URL$ --bitrate 320 --disable-discovery --disable-audio-cache $START$ | [flac] -cs --channels=$CHANNELS$ --sample-rate=$SAMPLERATE$ --bps=$SAMPLESIZE$ --endian=little --sign=signed --fast --totally-silent --ignore-chunk-sizes -

I have modified my copy of Spotty's custom-convert.conf to test this spt-flac transcoding rule, currently playing using slimserver 8.2. So far so good.

Happy New Year!

Edit: I had to comment out my spt->ogg rule to enable spt->flac, now streaming 705 kbps flac to my RPi Zero running squeezelite.