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Recent Posts
1
FLAC / Undithered digital silence causing problems
Last post by ktf -
On the FLAC github, quite a few people have shared that they have problems with live streaming or seeking in FLAC files that contain a lot of (undithered) digital silence. See here and here.

The issue is that when a FLAC encoder encounters digital silence, it uses the highly efficient constant subframes. On 44.1kHz audio using the default blocksize, the bitrate drops to about 1.3kbit/s for all bitrates and number of channels. For CDDA, which can peak to 1412kb/s this is a range of over 1:1000, for multichannel and 24-bit audio, this gets even worse. Seeking gets difficult because of the large fluctuations in frame size and streaming gets difficult because buffers run empty.

At first I thought this should be non-issue, as all audio should be dithered. However, requiring dithering isn't really lossless and not really user-friendly either. So, I wrote this bit of code which prevents the FLAC encoder from outputting frames that only contain constant subframes. With this code, the minimum bitrate the FLAC encoder uses (for 44.1kHz audio, irrespective of the number of channels or the bit depth) becomes 45.4kbit/s.

I could change libFLAC to include a switch somewhere to trigger this behaviour, but that would also require streaming software using libFLAC to be changed to benefit. Moreover, that wouldn't solve the seeking issue, which can be a problem to any user. I suspect the minimum bitrate increase isn't really an issue for normal users (i.e. it won't hurt compression for most music) because frames with only constant subframes won't happen often in music. Perhaps it should be disabled when --lax is used, because --lax can be used to create non-streamble FLAC files.

However, I'd like to know what you think.  :))
2
General Audio / Re: Lossless audio - we have space on todays portables. Comparisons
Last post by saratoga -
Yeah, https://www.rockbox.org/wiki/CodecPerformanceComparison illustrates how FLAC was optimized for decoding efficiency.

Like, iPod Nano: FLAC decoding three to four times as fast as MP3 (... and Apple Lossless).
And a three-minute song of Monkey's Insane would decode in less than two hours, yay!

Even more impressive, take a look at my numbers here for FLAC:  https://hydrogenaud.io/index.php?topic=82125.msg713417#msg713417

7 MHz for real-time decode stereo at 44.1 KHz.  That is just 80 clock cycles per output sample.  That is so few operations you could actually sit down and start calculating FLAC sample values on pen and paper in a reasonable time frame, 
6
AAC - General / Re: Which codec Spotify started using on their latest mobile app?
Last post by Porcus -
According to https://artists.spotify.com/help/article/audio-file-formats , they use:
* Ogg/Vorbis (96, 160, 320 kbps)
* AAC (128, 256 kbps)
* HE-AACv2 (24kbps)


The only thing I found is a confirmation that they seem to be using AAC exclusively: https://support.spotify.com/us/article/audio-quality/
That one specifies AAC for the web player, and is silent on what format is used in the other clients.

I take it that AAC is the way they can get DRM into the web player?
8
General Audio / Re: wanted: damaged sample files (lossless, lossy)
Last post by C.R.Helmrich -
i'd need to know what's broken so i can test for the particular problem, however a fuzz tester may come in handy also - thanks for mentioning
Not sure if what I have here qualifies (since I don't know what's broken), but: recently I got a (previously valid) broken FLAC and MP3 file caused by some choking, or hardware cell damage, when I copied those files from an SD card. I can't share them here since they are more than 30 seconds long (and that would violate the forum's ToS), so I'll try to get them to you in other ways.

Chris
10
3rd Party Plugins - (fb2k) / Re: Biography Discussion
Last post by mygen -
Hi

I have a issue with aritist photo display. Don't show from last.fm. I have fresh install SMP 1.5.2 + Biography 1.2.0.

When i switch on cover it is but photo artist no.

I install fresh many times and not working. Reset to default not working.

Maybe on settings its wrong?

Some idea what should i do?

Thx for replay.