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2nd September 2024, 15:12 | #1 | Link |
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best options for mono encoding ffmpeg libpous.
Hi i I am Rupesh from India and I brought a new pc with AMD Ryzen zen3 5500GT APU and Asus prime b450 motherboard and installed Linux Fedora 40 and I have some aac m4a music files and I want to convert them to opus files.
I installed libopus and libfdk-aac and compiled ffmpeg with options successfully using the following command --enable_libopus and --enable_libfdk-aac I want to convert aac m4a music files to opus using ffmpeg and libopus and so I have created a small bash script as follows. Code:
#/bin/bash for i in *.mp4; do name="${i%????}"; echo $name; ffmpeg -y -i "$i" -f mp4 -vn -ac 1 -c:a libopus -vbr on -application audio -mapping_family 0 -b:a 20k -af aresample=resampler=soxr -ar 48000 "${name}.opus"; done So for encoding from stereo to mono I have chosen option which is implied to libopus as Code:
-ac 1 mapping_family 0 I have even choosen the following options which are related to vbr mode and the output audio is music not speech. Code:
-vbr on -application audio If you think some other options need to be added to the above script suggest them also. Regards, Rupesh. |
2nd September 2024, 19:25 | #4 | Link |
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You can remove vbr on, application audio, and mapping_family because they're already set to those defaults. For the resampler, use:
Code:
-af resample=48000:resampler=soxr I believe xHE-AAC beats Opus in the lower-bitrate domain, but is more difficult to encode and decode, from a compatability point of view. Last edited by GeoffreyA; 2nd September 2024 at 19:40. |
3rd September 2024, 09:16 | #5 | Link |
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I did some quick testing this morning. Firstly, one doesn't need to set 48 kHz because it is converted to that implicitly. (Add "-loglevel debug" for more insight into what the filtergraph is doing behind the scenes.) So, a shorter, cleaner command might be:
Code:
ffmpeg -i INPUT -ac 1 -af aresample=resampler=soxr -c:a libopus -b:a 20k OUTPUT |
3rd September 2024, 16:10 | #9 | Link |
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Being on Windows, I'm not sure how to compile FFmpeg with Exhale support, Exhale being the USAC/xHE-AAC encoder. Perhaps try to find an Exhale build for Linux. Note that compatibility is still a problem. At any rate, audio below 64 kbps will not be that good.
https://gitlab.com/ecodis/exhale If you get hold of an Exhale build, you could pipe the audio from FFmpeg. Last edited by GeoffreyA; 3rd September 2024 at 16:16. |
3rd September 2024, 16:33 | #10 | Link |
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I think that xheaac is not fully implemented I mean development and testing work is going on and it takes few years to get full support.
I have searched Google for xheaac but unfortunately I found few results which are considerable. If you search for other encoders for example lame, aac you can get thousands of webpages related to documentation, operating systems support etc.,. |
3rd September 2024, 18:39 | #13 | Link |
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https://www.ffmpeg.org/ffmpeg-codecs.html#libopus-1
According to the documentation, mapping_family controls how the codec works with mono, stereo, or surround-sound input. A value of 0 is for mono and stereo input; 1 for surround, or more than two channels; and 255 for independent streams with an unspecified layout. By default, mapping_family has a value of -1, which, if the input is mono or stereo, picks the right setting of 0 automatically. But if your audio has more than two channels, set it to 1, which will turn on surround-sound masking and LFE optimisations. |
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ffmpeg, libopus, mono, options |
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