[Mp4-tech] Re: AAC LTP conformace files: Invalid MP4 headers?

[Ralph Sperschneider]

Dear Eddie,
this informs you that we have updated the sequences in question. We kindly 
appreciate your cross-check.
Best regards,
Ralph
Ralph Sperschneider wrote:
> Dear Eddie,
> 
> thanks for this valuable information. We can confirm your observataion 
> (moov.trak.mdia.mdhd.timescale is 3) as well as your conclusion (it 
> should be 48000). Most likely, the generator has provided the 
> sampling_frequency_index instead of the sampling frequency. We observed 
> that some related fields (moov.mvhd.duration, moov.track.tkhd.duration 
> equals 144384000) are also wrong (should be 9024), but consistent with 
> the wrong timescale. We are going to fix this.
> 
> Best regards,
> 
> Ralph
> 
> 
> Eddie Choy wrote:
> 
>> Hello all,
>>
>> We downloaded the latest AAC LTP conformance bitstreams from  
>> _ftp://mpaudconf:adif2mp4@ftp.iis.fhg.de/mpeg4audio-conformance_, 
>> namely ap01_48.mp4, ap02_48.mp4, ap03_48.mp4, ap04_48.mp4 and 
>> ap05_48.mp4.  We noticed that the "timescale" field in the "mdhd" atom 
>> contains the value "3" in all these files.  This is not quite correct 
>> as these files are at 48 kHz (sampling rate) and this field should 
>> have been set to 48000.  Does anybody notice this problem?
>>
>> Regards,
>> Eddie
>>
>>
>> ------------------------------------------------------------------------
>>
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> 
> 

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Dipl.-Ing. Ralph Sperschneider  | Phone: +49 9131 776 344
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