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Hello,
do you know if there is a list with the minimum and maximum values of the VBR Quality parameter (-q:a) for each encoder of FFMPEG ?
What were they thinking of when they did not publish this ?
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AFAIK it only works for mp3. You can set it from 1-10. You can check it out on the final file size with e.g. MediaInfo. Values higher than 10 don't give any change.
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from my tests i found out that it also works for
aac,libvorbis,speex.
what's the point of having a parameter if it does not work for all lossy encoders.
if it does not work why don't they just print a message that this parameter does not work for this encoder !! -
How did you check that out! I tried it on AAC but didn't see any change in file size like I see with mp3.Originally Posted by alexander121
FFmpeg passes through a lot without any notice that it isn't applicable on the selected codec. FFmpeg is mainly a sandbox for developers at which we are allowed to play with their built castles.what's the point of having a parameter if it does not work for all lossy encoders.
if it does not work why don't they just print a message that this parameter does not work for this encoder !!
Aside from that, most audio codecs come from "third party" developers. If their code doesn't support a quality option, FFmpeg cannot offer it with the -q:a command.
Chris -
Does CABAC work for MPEG2? No. Does CRF work for MPEG1? No. Does HBR work for MP2? No.
Each type of encoder (lossy or lossless) has parameters that are particular to it, or to its class/family. Many parameters are not universal. Doesn't mean there is no point to having it available for the codec it DOES work with.
Should the documentation be better? SURE! Since those FOSS things are often volunteer efforts, why don't you agree to take that on?! No? Maybe that's because you are busy like the rest of us and have to prioritize (which is what they're doing).
Scott -
actually i tried again the q:a parameter and it indeed works.
the file sizes differ.
here are the results..
regarding my comments for ffmpeg i think they should charge Google more for having such a great software used by Google Chrome
Code:c:\1>ffmpeg -i natgeo.mp4 -vn -strict -2 -c:a aac -q:a 0 a.aac ffmpeg version N-68625-g1728659 Copyright (c) 2000-2014 the FFmpeg developers built on Dec 19 2014 22:02:36 with gcc 4.9.2 (GCC) configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca -- enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-lib modplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrw b --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinge r --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --en able-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable- libx265 --enable-libxavs --enable-libxvid --enable-decklink --enable-zlib libavutil 54. 15.100 / 54. 15.100 libavcodec 56. 16.100 / 56. 16.100 libavformat 56. 16.101 / 56. 16.101 libavdevice 56. 3.100 / 56. 3.100 libavfilter 5. 4.100 / 5. 4.100 libswscale 3. 1.101 / 3. 1.101 libswresample 1. 1.100 / 1. 1.100 libpostproc 53. 3.100 / 53. 3.100 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'natgeo.mp4': Metadata: major_brand : isom minor_version : 1 compatible_brands: isom creation_time : 2012-07-09 11:58:52 Duration: 00:01:00.29, start: 0.000000, bitrate: 1932 kb/s Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709/ unknown/unknown), 720x406, 1800 kb/s, 25 fps, 25 tbr, 25k tbn, 50 tbc (default) Metadata: creation_time : 2012-07-08 08:37:43 handler_name : Video Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, flt p, 128 kb/s (default) Metadata: creation_time : 2012-07-08 08:37:49 handler_name : GPAC ISO Audio Handler File 'a.aac' already exists. Overwrite ? [y/N] y Output #0, adts, to 'a.aac': Metadata: major_brand : isom minor_version : 1 compatible_brands: isom encoder : Lavf56.16.101 Stream #0:0(eng): Audio: aac, 48000 Hz, stereo, fltp, 128 kb/s (default) Metadata: creation_time : 2012-07-08 08:37:49 handler_name : GPAC ISO Audio Handler encoder : Lavc56.16.100 aac Stream mapping: Stream #0:1 -> #0:0 (aac (native) -> aac (native)) Press [q] to stop, [?] for help size= 980kB time=00:01:00.28 bitrate= 133.2kbits/s video:0kB audio:961kB subtitle:0kB other streams:0kB global headers:0kB muxing o verhead: 2.011527% c:\1>dir a.aac Volume in drive C has no label. Volume Serial Number is A668-762F Directory of c:\1 03/03/2015 08:36 PM 1,003,569 a.aac 1 File(s) 1,003,569 bytes 0 Dir(s) 160,578,973,696 bytes free c:\1>ffmpeg -i natgeo.mp4 -vn -strict -2 -c:a aac -q:a 5 a.aac ffmpeg version N-68625-g1728659 Copyright (c) 2000-2014 the FFmpeg developers built on Dec 19 2014 22:02:36 with gcc 4.9.2 (GCC) configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca -- enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-lib modplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrw b --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinge r --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --en able-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable- libx265 --enable-libxavs --enable-libxvid --enable-decklink --enable-zlib libavutil 54. 15.100 / 54. 15.100 libavcodec 56. 16.100 / 56. 16.100 libavformat 56. 16.101 / 56. 16.101 libavdevice 56. 3.100 / 56. 3.100 libavfilter 5. 4.100 / 5. 4.100 libswscale 3. 1.101 / 3. 1.101 libswresample 1. 1.100 / 1. 1.100 libpostproc 53. 3.100 / 53. 3.100 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'natgeo.mp4': Metadata: major_brand : isom minor_version : 1 compatible_brands: isom creation_time : 2012-07-09 11:58:52 Duration: 00:01:00.29, start: 0.000000, bitrate: 1932 kb/s Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709/ unknown/unknown), 720x406, 1800 kb/s, 25 fps, 25 tbr, 25k tbn, 50 tbc (default) Metadata: creation_time : 2012-07-08 08:37:43 handler_name : Video Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, flt p, 128 kb/s (default) Metadata: creation_time : 2012-07-08 08:37:49 handler_name : GPAC ISO Audio Handler File 'a.aac' already exists. Overwrite ? [y/N] y Output #0, adts, to 'a.aac': Metadata: major_brand : isom minor_version : 1 compatible_brands: isom encoder : Lavf56.16.101 Stream #0:0(eng): Audio: aac, 48000 Hz, stereo, fltp, 128 kb/s (default) Metadata: creation_time : 2012-07-08 08:37:49 handler_name : GPAC ISO Audio Handler encoder : Lavc56.16.100 aac Stream mapping: Stream #0:1 -> #0:0 (aac (native) -> aac (native)) Press [q] to stop, [?] for help size= 1438kB time=00:01:00.28 bitrate= 195.4kbits/s video:0kB audio:1419kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.362200% c:\1>dir a.aac Volume in drive C has no label. Volume Serial Number is A668-762F Directory of c:\1 03/03/2015 08:37 PM 1,472,512 a.aac 1 File(s) 1,472,512 bytes 0 Dir(s) 160,578,494,464 bytes free -
Ok! You use the internal experimental aac encoder. Good to know it works.Originally Posted by alexander121
I used libvo_aacenc which seems to not support this feature (unless I've missed something).
Chris
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