album art images change kbps rate

[soundpimp]

I have observed that embedded album art increases the kbps rate of FLAC files. The file size is divided by the lenght of the audio file, hence kilobytes per second. The effect is more noticeable the shorter the tracks are. Keep in mind that when the specific track is not played, opening its info/tags box displays the correct (?) bitrate, which then changes (increases) when played. It seems a bit odd to me. Am I missing something when I say that kbps is supposed to indicate the audio data transmission and demonstrate the audio quality (partially) that way, or is everything working as intended? I only noticed this behavior in Poweramp so far. Kind of reminds me of that one problem back in the day where MP3 album art would increase the lenght of tracks. Thanks for any advice!

[maxmp]

Flac should contain this info in the file header. If it doesn't and there is something weird with the tags as well, the estimation (which happens then) may be off. There is any kind of weirdness for the files in the wild and I can say for sure and may be add some workaround if you share the file for tests with gpmaxmpz@gmail.com

Thanks!

[soundpimp]

Literally every FLAC file of mine applies. Maybe it's because I use Mp3tag to embed the album art? Can't tell for sure. I'll send some files.

[6b6561]

You can also push the files to https://mediaarea.net/MediaInfoOnline and see what header data you have in the file. Should give output like:

Format                                   : FLAC
Format/Info                              : Free Lossless Audio Codec
File size                                : 414 MiB
Duration                                 : 1 h 2 min
Overall bit rate mode                    : Variable
Overall bit rate                         : 924 kb/s
Album replay gain                        : -0.56 dB
Album replay gain peak                   : 0.894745

 

[soundpimp]

Does that mean that when Poweramp displays the increased kbps rate (with the embedded image) it is actually the overall bitrate and is therefore correct? Or is it supposed to show the audio bitrate only? I mean what is the point of seeing the overall bitrate? It's not like the cover art is partially loaded every second, right? I thought that the bitrate is supposed to indicate sound quality... maybe a setting could be implemented that lets the user decide which bitrate is being displayed.

[maxmp]

@soundpimp for Poweramp and flac, the bit rate estimation during tag scan differs from the playback estimation. The first one excludes tag size, but the playback estimation (as implemented in ffmpeg) uses whole file size for the estimation, including metadata. This is usually OK for the moderate image sizes, but if you push very large image for some reason, indeed it offsets displayed bitrate while playing.

Thanks!

[soundpimp]

So if I want to avoid this issue AND keep artworks embedded, I'd have to switch to ALAC... It doesn't care if the image is 10MB, the kbps rate stays the same! It even removes the padded file space after you remove the artwork!

[soundpimp]

Now the tag scan bitrate estimation for all ALAC files is at 1536/1411 kbps somehow... it is probably the AIFF/WAV file bitrate it was converted from. I think I can live with that tradeoff, since the playback estimation is correct now.

Edited September 7, 2023 by soundpimp