#9057 closed defect (fixed)
AAC 7.1 channels mixed up in decoding
Reported by: | kmamal | Owned by: | |
---|---|---|---|
Priority: | important | Component: | avcodec |
Version: | git-master | Keywords: | aac regression |
Cc: | Blocked By: | ||
Blocking: | Reproduced by developer: | no | |
Analyzed by developer: | no |
Description
Summary of the bug:
I have an 8 channel audio file that I'm encoding as AAC. When inspecting the channels of the created aac file using ffmpeg, they appear to be in the wrong order or even added together.
This appears to be a problem in decoding, as inspecting the aac file with other software (I used Audacity) shows the channels in the correct order.
This problem appeared in ffmpeg 4.3. In ffmpeg 4.2.4 the channels are ok.
How to reproduce:
I'm using the 8_Channel_ID.wav file attached to this ticket.
I'm encoding to AAC using:
ffmpeg -i 8_Channel_ID.wav out.aac
First I inspect the channels using:
ffmpeg -i out.aac -filter_complex "showwavespic=s=1280x480:split_channels=1" -frames:v 1 -f image2 - | display
The result looks like the first two channels have been swapped with the last two.
Then I inspect the channels using:
ffmpeg -i out.aac -filter_complex "channelsplit=channel_layout=7.1,join=inputs=8:channel_layout=7.1,showwavespic=s=1280x480:split_channels=1" -frames:v 1 -f image2 - | display
The result looks like the last two channels have been added to the first two.
Attachments (1)
Change History (5)
comment:1 by , 4 years ago
comment:2 by , 4 years ago
Did a git bisect and the problem first appeared in 4d9b9c5e4637ac15205467f16fcac92a28e18f18
comment:3 by , 4 years ago
I'm guessing layout_map[2][2] = AAC_CHANNEL_SIDE; still needs to be set on every call? I'll attach a proposed patch.
by , 4 years ago
Attachment: | fix2.patch added |
---|
comment:4 by , 4 years ago
Component: | undetermined → avcodec |
---|---|
Keywords: | aac regression added |
Priority: | normal → important |
Resolution: | → fixed |
Status: | new → closed |
Version: | unspecified → git-master |
Pushed as fbe9b0c8f3ee1ff1d36c6a6cd7fe6fc0c6a9e80d, thank you for the report and the fix!
File is too big to attach so I'm linking it: https://www.dropbox.com/s/5uyzuuz0wgvn5t4/8_Channel_ID.wav?dl=0