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11th August 2020, 18:47 | #1 | Link | ||
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weird FLAC compression
Hi,
I have a PCM file - LPCM Audio / 2.0 / 48 kHz / 1536 kbps / 16-bit Encoded with 2 FLAC versions and the outputs are 1) libFLAC 1.2.1 (using eac3to) Quote:
Quote:
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11th August 2020, 19:46 | #2 | Link |
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Is your FLAC build with Visual Studio and 64-bit? There has been an odd bug that caused files to barely compress when Visual Studio compiles libFLAC in 64-bit mode. Newer libFLAC has a work-around for this issue, ie. you could get 1.3.3
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11th August 2020, 20:40 | #3 | Link | |
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Thanks nevcairiel for the reply.
I just tried 1.3.3 from https://www.videohelp.com/software/FLAC-Encoder (win64-bit) but same result (bloated flac). Quote:
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11th August 2020, 22:39 | #4 | Link |
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A wav 1 h 43 min at 1536 kbps (2.0, 48000, 16bit) have a size of 1.2 GB, a flac compression to 882 MB is more or less normal (73%), a compression to 278 MB is not normal (23%). A tipical compression can be 60%.
The source have many silences to justify this 23%?
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BeHappy, AviSynth audio transcoder. Last edited by tebasuna51; 11th August 2020 at 22:46. |
12th August 2020, 15:34 | #5 | Link | |
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Quote:
But how come the very old version of FLAC compresses a lot more ( 23% vs 73%) than the latest FLAC version? I'm able to reverse the flac file back to PCM and hash check (they matched) for both versions. |
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12th August 2020, 18:11 | #6 | Link |
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I can't confirm than v1.2.1 compress more.
With 1 hour wav (from Jurassic Park) test: Code:
Size (bytes) enc. time % ------------------------- ------------- --------- ------ WAV 5.1,1 hour,48kHz,24 b 3.110.400.102 - flac.exe -5 1.3.3 64 b 1.708.546.600 22,68 54,930 flac.exe -5 -e 1.3.3 64 b 1.707.631.271 45,34 54,901 ffmpeg -5 Lavf58.42.100 1.707.221.663 23,63 54,887 eac3to libflac 1.2.1 32 b 1.705.970.954 3:43,90 54,847 flac.exe -8 1.3.3 64 b 1.705.443.722 38,95 54,830 flac.exe -8 -e 1.3.3 64 b 1.705.443.722 43,39 54,830 eac3to libflac 1.3.3 32 b 1.705.367.448 1:19,47 54,828 ffmpeg -12 Lavf58.42.100 1.704.010.142 5:16,12 54,784 I used best size (-8 in flac.exe), if I remember ok madshi use also -8 by default. with ffmpeg I used -compression_level 12, I don't know how reproduce that with flac, we obtain the best size (only a 0,05 % better) but with huge encoding time. EDIT: more encode options. If default for flac and ffmpeg (compression level 5) is more compatible with hardware players, like SeeMoreDigital say, I think is the best option because the gain in size is only a 0,1 %
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BeHappy, AviSynth audio transcoder. Last edited by tebasuna51; 13th August 2020 at 11:54. Reason: add info |
13th August 2020, 09:55 | #8 | Link |
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Same size with -8 -e:
Code:
flac.exe -8 1.3.3 64 b 1.705.443.722 38,95 54,830 flac.exe -8 -e 1.3.3 64 b 1.705.443.722 43,39 54,830 flac.exe -5 -e 1.3.3 64 b 1.707.631.271 45,34 54,901 flac.exe -5 1.3.3 64 b 1.708.546.600 22,68 54,930 Flac.exe -8 is a good option for me. Of course I don't know for what libflac 1.2.1 32 bits compress the bjoker file with a 23%
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BeHappy, AviSynth audio transcoder. Last edited by tebasuna51; 13th August 2020 at 10:23. |
13th August 2020, 10:36 | #9 | Link |
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For anyone who is interested...
The 'Compression 5' setting is more compatible with hardware playback devices
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13th August 2020, 11:25 | #10 | Link |
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I encoded atleast 50 PCMs to FLAC and the difference has always been <20% between 1.2.1 & 1.3.2 but this one is different.
Not sure what compression level does eac3to use (I think it is 5) but I used default setting. I tried 1.3.2 (& 1.3.3) with default & "--compression-level-5" but same result. There seems to be no way of finding the compression level of a FLAC file. Could i upload the whole audio (or part of it) to a file hoster and share here so anyone with interest could reproduce the problem? Thanks everyone for your replies |
13th August 2020, 11:58 | #11 | Link |
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@SeeMoreDigital
Good to know, I modified the table with the comparative. I I will modify the default for encode to flac with ffmpeg in Useac3to GUI. @bjoker Don't upload the file for me, I believe in your test and I can't do anything more with it. The eac3to compression level is the max (I suppose 8) like madshi say here
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BeHappy, AviSynth audio transcoder. Last edited by tebasuna51; 13th August 2020 at 12:07. Reason: add info |
13th August 2020, 12:38 | #12 | Link |
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If you post the issue at https://sourceforge.net/p/flac/bugs/ , maybe some dev will be able to see what the difference between the files is. As far as I've understood, eac3to uses a standard library for FLAC so it should be possible to reproducible with a build from the same sources.
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