Alexa can now handle FLAC streams

[philchillbill]

I've submitted a PR here https://github.com/Logitech/slimserver/pull/606 but I think you should try it more because I think there are still various challenges with trying to stream flac like that.

Much appreciated Philippe. I've dropped the 5 files from your PR into my existing install and after a restart of LMS the /stream.flac path is indeed available. It plays just fine on an Echo but I have no way of knowing what the stream actually is that the Echo is receiving. In iPeng, the AlexaPlayer shows up and if I click on 'more info' when streaming a FLAC file, I see this:

That would seem to imply that the stream is an MP3 conversion from FLAC rather than native FLAC, or am I misunderstanding?

[philippe_44]

Much appreciated Philippe. I've dropped the 5 files from your PR into my existing install and after a restart of LMS the /stream.flac path is indeed available. It plays just fine on an Echo but I have no way of knowing what the stream actually is that the Echo is receiving. In iPeng, the AlexaPlayer shows up and if I click on 'more info' when streaming a FLAC file, I see this:

That would seem to imply that the stream is an MP3 conversion from FLAC rather than native FLAC, or am I misunderstanding?

I missed that answer.

Not sure re mp3, it might be a display artefact that I've forgotten to fix. I'll check that. Can you try with a client like VLC or fb2k?

[philchillbill]

I missed that answer. No, the mp3 reference is a display artefact that I've forgotten to fix

Well everything I tested played perfectly from an audio perspective. Did see a metadata artefact for the first song in a playlist where part of the name of the track was a placeholder instead of the tag. But really great progress I would say !

[philchillbill]

Can you try with a client like VLC or fb2k?

Same story in VLC. It plays just fine but the stream is shown as being lossy (see above). What I noticed today is that playing the stream in the browser tried to download a stream.flac file rather than start an audio stream, as if the MIME header was wrong. After a few retries it became an audio stream. Strange.

[philippe_44]

Same story in VLC. It plays just fine but the stream is shown as being lossy (see above). What I noticed today is that playing the stream in the browser tried to download a stream.flac file rather than start an audio stream, as if the MIME header was wrong. After a few retries it became an audio stream. Strange.

Weird... I've tried with VLC and got confirmation that it's flac. I'm wondering if either I forgot to put something in the PR or you missed something in applying it

[philchillbill]

Weird... I've tried with VLC and got confirmation that it's flac. I'm wondering if either I forgot to put something in the PR or you missed something in applying it

I saw 5 changed files in the PR, so on my Ubuntu install, I stopped LMS and copied:

silence.flac and silence-header.flac to /usr/share/squeezeboxserver/HTML/EN/html
convert.conf to /usr/share/squeezeboxserver
HTTP.pm to /usr/share/perl5/Slim/Player
the other HTTP.pm to /usr/share/perl5/Slim/Web

I then did a sudo chown root:root on all the copies filed and restarted LMS

TBH I'm not sure why my LMS has files in /usr/share/squeezeboxserver and in /usr/share/perl5 so maybe my approach in applying your PR to my existing install was wrong.

[philippe_44]

I saw 5 changed files in the PR, so on my Ubuntu install, I stopped LMS and copied:

silence.flac and silence-header.flac to /usr/share/squeezeboxserver/HTML/EN/html
convert.conf to /usr/share/squeezeboxserver
HTTP.pm to /usr/share/perl5/Slim/Player
the other HTTP.pm to /usr/share/perl5/Slim/Web

I then did a sudo chown root:root on all the copies filed and restarted LMS

TBH I'm not sure why my LMS has files in /usr/share/squeezeboxserver and in /usr/share/perl5 so maybe my approach in applying your PR to my existing install was wrong.

Got it - I missed what happens when the URL contains a player's name (like stream.flac?player=Alexa) and that caused the issue (it changes for how long LMS remembers a player after it disappeared). I've updated the PR

[philchillbill]

Got it - I missed what happens when the URL contains a player's name (like stream.flac?player=Alexa) and that caused the issue (it changes for how long LMS remembers a player after it disappeared). I've updated the PR

I dropped in that one changed file (Slim/Web/HTTP.pm) and indeed VLC now showed the stream as FLAC for the first attempt at playing something. However, exiting VLC and then restarting the same file now showed it as MPEG. I also saw a few times with playing in the browser an attempt to download a file called stream.flac rather than play it as audio, so looks like the MIME/haeder issue might still be there. I have never seen that with /stream.mp3.

Have you tried "Forget this player" in the WEB UI using Settings --> Player --> VLC from Alexa --> Forget this player? It works fine when the player was created via /stream.mp3 but not when /stream.flac is used.

Also, player controls like next/previous seem to work sometimes and sometimes not.

[philippe_44]

I dropped in that one changed file (Slim/Web/HTTP.pm) and indeed VLC now showed the stream as FLAC for the first attempt at playing something. However, exiting VLC and then restarting the same file now showed it as MPEG. I also saw a few times with playing in the browser an attempt to download a file called stream.flac rather than play it as audio, so looks like the MIME/haeder issue might still be there. I have never seen that with /stream.mp3.

Have you tried "Forget this player" in the WEB UI using Settings --> Player --> VLC from Alexa --> Forget this player? It works fine when the player was created via /stream.mp3 but not when /stream.flac is used.

Also, player controls like next/previous seem to work sometimes and sometimes not.

ah crap... I need to investigate more. Difficulty is that although flac is fully streamable w/o header, some "players" want a header, still. MP3 does not suffer from that.

I also do my tests with fb2k so I’ll add VLC systematically now

[philippe_44]

ah crap... I need to investigate more. Difficulty is that although flac is fully streamable w/o header, some "players" want a header, still. MP3 does not suffer from that.

I also do my tests with fb2k so I’ll add VLC systematically now

I think I'll have to give up on this one. There are too many issues with a flac continuous stream.

Normally, flac is supposed to be streamable because it has paquets delimiters like mp3 and each paquet is self-contained, which makes headers optional. Unfortunately, most players I've tried want headers. Then the ones that can just work with paquets can't accept sampling rate change in the stream (which will happen as this is a continuous stream but with different tracks - again mp3 allows that). Then when playing local files, LMS might not transcode them (flac) and in that case they have a full flac header which confuses even more players that can accept raw paquet (they can't recover flac sync properly).

On paper, this should work according to flac specs, but in practice it does not