On Thu, Feb 9, 2023 at 9:24 PM Jan Ekström <jee...@gmail.com> wrote:
>
> On Thu, Feb 9, 2023 at 12:08 PM Martin Storsjö <mar...@martin.st> wrote:
> >
> > This looks reasonable to me. I didn't follow the references in the commit
> > message, but it sounds plausible and probably correct to me.
> >
>
> For the record, due to dumb ISO/IEC rule changes regarding how
> specifications need to be authorized to be free after 2015, it's
> relatively hard to verify the 14496-12 part.
>
> The last version of 14496-12 that was freely available (2015) defined
> channelcount in AudioSampleEntry as follows:
>
> template unsigned int(16) channelcount = 2;
>
> Meanwhile the latest 2022 edition defines the related structure(s) as follows:
>
> class AudioSampleEntry(codingname) extends SampleEntry (codingname) {
> const unsigned int(32)[2] reserved = 0;
> unsigned int(16) channelcount;
> template unsigned int(16) samplesize = 16;
> unsigned int(16) pre_defined = 0;
> const unsigned int(16) reserved = 0 ;
> template unsigned int(32) samplerate = { default samplerate of media} <<
> 16;
> // optional boxes follow
> Box (); // further boxes as needed
> ChannelLayout();
> DownMixInstructions() [];
> DRCCoefficientsBasic() [];
> DRCInstructionsBasic() [];
> DRCCoefficientsUniDRC() [];
> DRCInstructionsUniDRC() [];
> // we permit only one DRC Extension box:
> UniDrcConfigExtension();
> // optional boxes follow
> SamplingRateBox();
> ChannelLayout();
> }
>
> aligned(8) class SamplingRateBox extends FullBox('srat') {
> unsigned int(32) sampling_rate;
> }
>
> class AudioSampleEntryV1(codingname) extends SampleEntry (codingname) {
> unsigned int(16) entry_version; // shall be 1,
> // and shall be in an stsd with version ==1
> const unsigned int(16)[3] reserved = 0;
> template unsigned int(16) channelcount; // shall be correct
> template unsigned int(16) samplesize = 16;
> unsigned int(16) pre_defined = 0;
> const unsigned int(16) reserved = 0 ;
> template unsigned int(32) samplerate = 1<<16;
> // optional boxes follow
> SamplingRateBox();
> Box (); // further boxes as needed
> ChannelLayout();
> DownMixInstructions() [];
> DRCCoefficientsBasic() [];
> DRCInstructionsBasic() [];
> DRCCoefficientsUniDRC() [];
> DRCInstructionsUniDRC() [];
> // we permit only one DRC Extension box:
> UniDrcConfigExtension();
> // optional boxes follow
> ChannelLayout();
> }
Applied to master as 02ddfeadbee52c1ad8c023a93594a8cb957e11db .
Jan
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