How to set mFramesPerPacket in CoreAudio Encoder?

[pzs-scnu]

When converting audio to AAC, the encoder's mFramesPerPacket should be 1024, how to set this in encoder's settings? can it be set by .coreAudioAudioConverterPropertySettings ?
also, for AAC audio, the following properties in AudioStreamBasicDescription should be set:
mBitsPerChannel = 0 // Not used for AAC
mBytesPerFrame = 0 // Not used for AAC
mBytesPerPacket = 0 // Variable for AAC

[pzs-scnu]

I've modified SFBCoreAudioEncoder.mm and SFBAudioEncoder.h to add the following keys for CoreAudioEncoder:

SFBAudioEncodingSettingsKey const SFBAudioEncodingSettingsKeyCoreAudioFramesPerPacket = @"Frames per Packet";
SFBAudioEncodingSettingsKey const SFBAudioEncodingSettingsKeyCoreAudioBytesPerFrame = @"Bytes per Frame";
SFBAudioEncodingSettingsKey const SFBAudioEncodingSettingsKeyCoreAudioBytesPerPacket = @"Bytes per Packet";
Archive.zip

@sbooth Please check the attached file to see if the modification is appropriate.

[sbooth]

I don't see any problems per se with the code you posted but I am not sure it's necessary. At a minimum all fields in the AudioStreamBasicDescription are initially set to zero so there should be no need to set values to zero.

Using the following settings

encoder.settings = [
	.coreAudioFileTypeID: kAudioFileM4AType,
	.coreAudioFormatID: kAudioFormatMPEG4AAC,
]

I am able to create a working M4A file:

File:           piano.m4a
File type ID:   m4af
Num Tracks:     1
----
Data format:     2 ch,  48000 Hz, aac  (0x00000000) 0 bits/channel, 0 bytes/packet, 1024 frames/packet, 0 bytes/frame
                no channel layout.
estimated duration: 6.306500 sec
audio bytes: 104504
audio packets: 298
bit rate: 131506 bits per second
packet size upper bound: 691
maximum packet size: 691
audio data file offset: 62276
optimized
audio 302712 valid frames + 2112 priming + 328 remainder = 305152
format list:
[ 0] format:	  2 ch,  48000 Hz, aac  (0x00000000) 0 bits/channel, 0 bytes/packet, 1024 frames/packet, 0 bytes/frame
Channel layout: Stereo (L R)

What file type are you generating? Could you post a non-working example?