[Mp4-tech] [Audio] Bitrate from ADTS

[Ralph Sperschneider]

athorn io.com wrote:
> How would I do that?  Thanks!

bit_reservoir_state[frame]=bit_reservoir_state[frame-1]+mean_framelength-framelength[frame]
Ralph
> 
> 
>>Mody, Mihir wrote:
>>
>>
>>>Hi Ann,
>>>
>>>As AAC ADTS format doesn't have bitrate information, you have to use
>>>other means. The framelength of given audio frame will give you
>>>instantaneous bit-rate (as frame_length (in byte) * 8 * sampling
>>>frequency/1024). You can average out this bit-rate over certain number
>>>(say N) of frames to find out average bitrate.
>>>
>>
>>Or one could use the subsequent information on the bit reservoir status to
>>compute the mean frame length (just not bit exact, since the state of the
>>bit
>>reservoir is rounded).
>>
>>Ralph
>>
>>--
>>Dipl.-Ing. Ralph Sperschneider  | Phone: +49 9131 776 344
>>Fraunhofer IIS                  | Fax:   +49 9131 776 398
>>Am Wolfsmantel 33               |
>>mailto:ralph.sperschneider iis.fraunhofer.de
>>D 91058 Erlangen                | http://www.iis.fraunhofer.de/amm/
>>
> 
> 

-- 
Dipl.-Ing. Ralph Sperschneider  | Phone: +49 9131 776 344
Fraunhofer IIS                  | Fax:   +49 9131 776 398
Am Wolfsmantel 33               | mailto:ralph.sperschneider iis.fraunhofer.de
D 91058 Erlangen                | http://www.iis.fraunhofer.de/amm/