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

[Eddie Choy]

Dear Ralph,
We just re-downloaded the five LTP conformance sequences and they are ok 
now.  Thank you for your prompt response on this matter.
Regards,
Eddie
At 06:14 PM 9/12/2023 +0200, Ralph Sperschneider wrote:
>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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>
>--
>Dipl.-Ing. Ralph Sperschneider  | Phone: +49 9131 776 344
>FhG IIS                         | Fax:   +49 9131 776 398
>Am Wolfsmantel 33               | mailto:sps iis.fhg.de
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>