[Mp4-tech] [Audio] AMR payload&Storage format

[Mehdi Sharifi]

hi dear ,
  thanks for everything!
 there are two modes for AMR payload :  Octet-Aligned mode &  bandwidth efficient mode ;  but  how can I  recognize these two modes? I mean if there is some indicating value in  payload header to  determine the specific mode.
in 3GPP TS 26.101 "Adaptive Multi-Rate (AMR) speech codec frame structure"  , is the format of AMR frame  in  payload or in storage format ?
waiting for reply
--mehdi
Dave Singer <singer apple.com> wrote:
At 8:05 AM -0700 9/20/04, Mehdi Sharifi wrote:
Hi ,thanks for replying ,  in 3GPP file format  it is said that  format of  AMR samples  is  according to RFC 3267 ; I read RFC 3267 ; it was alittle complicated ; I am looking for a source or some contribution  to convert  this payload format to  ordinary AMR format  in order to  play it with QuickTime  or  another  player if you can help me , it's very appriciated thank you alot--mehdi
Well converting an RTP stream to a file format is a moderate amount of work.  In a 3GPP file, each media track is constructed as a sequence of timed samples.  The duration of AMR frames is constant (20ms as I recall).  The media data (as represented by the sample sizes etc.) is stored as 'samples' (frames).  Each sample consists of a set of AMR frames (as indicated by the frames-per-sample value), contiguously stored, in the 'storage format' , however, there is no magic number stored within the samples;  that is, each sample is just a contiguous set of AMR frames.
"Mody, Mihir" <mihir ti.com> wrote:
Hi Mehdi, Are you refering to storage format as per RFC 3267 or 3GPP file format based on MPEG4 File format? Regards,Mihir Mody,
Multimedia codecs group,
Texas Instruments India, Ltd,
Email : mihir ti.com
Phone : +91-80-25099307
-----Original Message-----
From: mp4-tech-bounces lists.mpegif.org [mailto:mp4-tech-bounces lists.mpegif.org]On Behalf Of Mehdi Sharifi
Sent: Monday, September 20, 2023 7:07 PM
To: mp4-tech lists.mpegif.org
Subject: [Mp4-tech] AMR payload&Storage format
  Hi dear all,  format of AMR  in storage is abit different from it's format  in payload or streaming .  is there any source code  that I can use to  convert  payload format to storage format ? thanx    --mehdi
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-- 
David Singer
Apple Computer/QuickTime
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