On Wed, Jul 11, 2012 at 9:45 AM, Kieran Kunhya <[email protected]> wrote: > On Wed, Jul 11, 2012 at 5:44 PM, Derek Buitenhuis > <[email protected]> wrote: >> On 11/07/2012 8:38 AM, Martin Storsjö wrote: >>> TODO: Are the mpeg2 ones official or specific to the fraunhofer >>> encoder? >>
The MPEG-2 ones are "fake." The word profile means very different things in MPEG-2 and MPEG-4. These are all profiles in the MPEG-2 sense of the word. In MPEG-4 these are audio object types (because it wouldn't be MPEG-4 if it wasn't all objects and descriptors). MPEG-4 profiles combine lists of AOTs that can be used together. More modern (and relevant) MPEG-4 profiles (The "AAC Profile" family) map to a single object type (and 0 or more enhancement object types). The MPEG-2 "AOTs" used by this encoder are just MPEG-4 AOTs shifted by 127. They can either by implemented with FF_PROFILEs or with a private option shifting us into MPEG-2 mode. >> >>> #define FF_PROFILE_AAC_LOW 1 >>> #define FF_PROFILE_AAC_SSR 2 >>> #define FF_PROFILE_AAC_LTP 3 >>> +#define FF_PROFILE_AAC_HE 4 >>> +#define FF_PROFILE_AAC_HE_V2 28 >>> +#define FF_PROFILE_AAC_LD 22 >>> +#define FF_PROFILE_AAC_ELD 38 >> >> Where these numbers come from is something that needs to >> be answered before push. >> > > AOT tables in ISO/IEC 14496-3 AOT minus 1, since MAIN is zero in MPEG-2 but in MPEG-4 NULL is zero and MAIN is one. _______________________________________________ libav-devel mailing list [email protected] https://lists.libav.org/mailman/listinfo/libav-devel
