iOS MP3 or AAC with CBR issues

[Craigy]

We are exporting MP3 and AAC files from Logic Pro / Itunes with a constant bit rate - however when we look at these in the terminal they are showing as having a 0 value for the bytes/packet - therefore the SDK is seeing them as VBR files... Here's an example in the terminal:

File: introduction.mp3
File type ID: MPG3
Data format: 2 ch, 44100 Hz, '.mp3' (0x00000000) 0 bits/channel, 0 bytes/packet, 1152 frames/packet, 0 bytes/frame
no channel layout.
estimated duration: 246.000 sec
audio bytes: 4938188
audio packets: 9452
bit rate: 160 bits per second
packet size upper bound: 1052
maximum packet size: 523
audio data file offset: 4096
optimized

Tried exporting them as AAC and MP3 using both Logic Pro and iTunes but all output files are showing a bytes/packet value.

Does anyone know how we can ensure that the CBR files have non 0 values for both bytes/packet and frames/packet?

 

[Craigy]

More info:

FO:
MPEG1 layer 3
9452 frames
44100 Hz
38.281250 frames per second
246.909388 seconds
4942284 bytes in file (160.132721 kbps)
4938188 bytes in MP3 frames (160.000008 kbps) = current bitrate
36500250 bits of payload data (147.828523 kbps)
4566717 bytes of payload data (147.964143 kbps)
33486 bits wasted from partially-full bytes (0.135621 kbps)
4906989 bytes of MP3 data (158.989143 kbps) = minimum bitrate possible
31199 bytes of padding (1.010865 kbps)
4096 bytes outside MP3 frames (0.132713 kbps)
0 sync errors
Bitrate distribution:
160: 5208,4244
Largest frame uses 6427 bits = 804 bytes = 246.033594 kbps
Smallest bitrate for CBR is 160