Changes between Version 57 and Version 58 of Encode/AAC

Timestamp:

Apr 21, 2023, 1:57:26 PM (3 years ago)

Author:

Mingye Wang

Comment:

native other profile; fdk ld and eld mention

Encode/AAC

@@ -123 +123 @@
 The native FFmpeg AAC encoder. This is currently the second highest-quality AAC encoder available in FFmpeg and does not require an external library like the other AAC encoders described here. This is the default AAC encoder.
 
-The native encoder is actually two encoders in a trench-coat. When a build is configured with --enable-audiotoolbox, the libavcodec implementation is swapped out for Apple's AudioToolbox.framework, normally available only on macOS. Apple's encoder is quite good and has HE-AAC support. You may have come across this implementation on other platforms as "QAAC" or "AudioToolboxWrapper", but licensing issues for these modifications is too much for FFmpeg to deal with.
+By default, the native encoder produces AAC-LC, which is a "low complexity" profile of baseline AAC. It actually supports the more powerful "main" and "long-term prediction" profiles ([[https://ffmpeg.org/ffmpeg-codecs.html#aac|documentation]]), but these are less tested.
+
+The native encoder is actually two encoders in a trench-coat. When a build is configured with --enable-audiotoolbox, the libavcodec implementation is swapped out for Apple's audioToolbox.framework, normally available only on macOS. Apple's encoder is quite good in listening tests and has HE-AAC support, so that the same `-profile:a` flags work. You may have come across this implementation on other platforms as "QAAC" or "audioToolboxWrapper", but licensing issues for these modifications is too much for FFmpeg to deal with.
 
 === Examples ===
@@ -188 +190 @@
 If you require a low audio bitrate, such as ≤ 32kbs/channel, then HE-AAC would be worth considering if your player or device can support HE-AAC decoding. Anything higher may benefit more from AAC-LC due to less processing. If in doubt use AAC-LC. All players supporting HE-AAC also support AAC-LC.
 
+You might see that FDK AAC also supports AAC-LD and AAC-ELD. These are low delay variants rarely used in music (hence unlikely to be supported), but useful for VoIP. In general, you will only turn it on when the receiving side  explicitly requires one of these variants.
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