Hi, I intend to add support for the xll extension to the dca decoder, aka "DTS-HD Master Audio", as requested on https://wiki.videolan.org/Bounties#List_of_bounties. I work at Southpole Consulting, together with Benjamin Larsson, and I'll hopefully be able to spend a couple of weeks of working time on this.
There are two parts of this project. First, implement the parsing and processing of the xll extension data. Second, reverse engineer whatever details of the fixed point decoding operations are needed to actually get bit exact lossless result, and implement them in libav. Resources I'm aware of: The spec itself. As far as I understand the 2012-09 version is the latest one. http://webapp.etsi.org/ewp/copy_file.asp?wki_id=39523 The wip patches at https://github.com/richardpl/FFmpeg/tree/xll Test files at https://samples.libav.org/A-codecs/DTS/dts/ A couple of questions: * the libavcodec/dcadec.c file look a bit different in ffmpeg and libav, and ffmpeg includes handling of the XXCH extension. I'm not yet familiar enough with dca to say how related this is to xll, but maybe it would make sense to first merge the ffmpeg changes to libav? (I don't know the history of the ffmpeg/libav split). * I tried libav's make check, and as far as I could see, there were no testcases specific for the dca decoder. Is that right, or have I missed something? * When I get to the bitexact part of this project, I'd need to have an "original" file (flac/wav, or whatever lossless format which is well supported in libav), and the same file compressed with dca and the xll lossless extension. The objective obviously being that the samples output from dcadec should be bit-by-bit identical to the original audio samples. Does anyone have such a set of test files? Outside of work, I'm involved in the GNU Nettle crypto library, and the GNU GMP bignum library. I'm new to libav. Regards, /Niels -- Niels Möller. PGP-encrypted email is preferred. Keyid C0B98E26. Internet email is subject to wholesale government surveillance. _______________________________________________ libav-devel mailing list libav-devel@libav.org https://lists.libav.org/mailman/listinfo/libav-devel
