Facing the same issue on the 14. When I look at AudioStreamBasicDescription of the CMSampleBuffer that are received from videoChat mode on 14, I get this
Optional(<CMAudioFormatDescription 0x283384820 [0x1f2fa8580]> {
mediaType:'soun'
mediaSubType:'lpcm'
mediaSpecific: {
ASBD: {
mSampleRate: 44100.000000
mFormatID: 'lpcm'
mFormatFlags: 0xc
mBytesPerPacket: 8
mFramesPerPacket: 1
mBytesPerFrame: 8
mChannelsPerFrame: 4
mBitsPerChannel: 16 }
cookie: {(null)}
ACL: {Mono}
FormatList Array: {
Index: 0
ChannelLayoutTag: 0x640001
ASBD: {
mSampleRate: 44100.000000
mFormatID: 'lpcm'
mFormatFlags: 0xc
mBytesPerPacket: 8
mFramesPerPacket: 1
mBytesPerFrame: 8
mChannelsPerFrame: 4
mBitsPerChannel: 16 }}
}
extensions: {(null)}
})
When I initialize audio session in default mode, the CMAudioFormatDescription of audio samples is
Optional(<CMAudioFormatDescription 0x282559540 [0x2021f4580]> {
mediaType:'soun'
mediaSubType:'lpcm'
mediaSpecific: {
ASBD: {
mSampleRate: 44100.000000
mFormatID: 'lpcm'
mFormatFlags: 0xc
mBytesPerPacket: 2
mFramesPerPacket: 1
mBytesPerFrame: 2
mChannelsPerFrame: 1
mBitsPerChannel: 16 }
cookie: {(null)}
ACL: {Mono}
FormatList Array: {
Index: 0
ChannelLayoutTag: 0x640001
ASBD: {
mSampleRate: 44100.000000
mFormatID: 'lpcm'
mFormatFlags: 0xc
mBytesPerPacket: 2
mFramesPerPacket: 1
mBytesPerFrame: 2
mChannelsPerFrame: 1
mBitsPerChannel: 16 }}
}
extensions: {(null)}
})
This shows that audio session is sending CMSampleBuffer objects that are now fundamentally different (this new format is not handled by AVAssetWriter and I get an error upon calling AVAssetWriter.append.
