On 5/26/17, Carl Eugen Hoyos <ceffm...@gmail.com> wrote: > 2017-05-25 22:39 GMT+02:00 Paul B Mahol <one...@gmail.com>: >> On 5/25/17, Carl Eugen Hoyos <ceffm...@gmail.com> wrote: >>> 2017-05-25 16:45 GMT+02:00 Paul B Mahol <one...@gmail.com>: >>> >>>> +@section surround >>>> +Apply audio surround upmix filter. >>>> + >>>> +This filter allows to produce multichannel output from >>>> stereo audio stream. >>> >>> Does this work on Pro Logic-encoded files (ticket #4085) >>> or does this filter use a different algorithm? >> >> It works with sample from that ticket. > >> It uses own algorithm. > > Is it related to one of the algorithms listed here? > https://en.wikipedia.org/wiki/Matrix_decoder > It may make sense to mention the used algorithm in the > documentation (or the source code).
All those are passive algorithms, while this one is active. > >>> Does a filter have advantages over an implementation in >>> libswresample? >> >> libswresample doesnt do this. > > Yes. > My question was if your implementation shouldn't be > part of libswresample, or rather what would be the > disadvantage. This filter relies on FFT, and it should probably stay in libavfilter library. > >>> Iirc, our Pro Logic downmixer has an issue with "phase shift" >>> (ticket 3455 / 4175): Does this filter give expected output >>> for FFmpeg-encoded files or original Pro Logic files (or is >>> there no difference on upmixing)? >> >> FFmpeg downmixing, while certainly not correct, is giving >> reasonable output when used with this filter. > > But it works better for Pro Logic files? I only have one such file, and its not that useful. FFmpeg have only downmixing from 5.1 layout to stereo. I also plan to add 5.1 to 7.1 upmixing. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
