On 23/03/2025 20:01, James Almer wrote: > On 3/22/2025 2:49 PM, Massimo Eynard wrote: >> This patch adds support for decoding the fourth MLP substream >> which contains the 16-channel presentation used for Atmos >> audio objects. >> >> By default only the first three substreams are decoded >> unless the new extract_objects flag is enabled as the resulting >> presentation contains audio object feeds instead of classic >> loudspeaker feeds. >> >> As this introduces interpolation of primitive matrices, precision >> has been increased to 2.18 fixed point. Therefore this requires >> DSP code upgrade which has been done for C and x86 implementations >> but not the ARM implementation. >> >> Adds two FATE tests using existing atmos.thd sample to reflect >> changes. >> >> Signed-off-by: Massimo Eynard <eynard.mass...@gmail.com> >> --- >> libavcodec/arm/mlpdsp_armv5te.S | 2 +- >> libavcodec/arm/mlpdsp_init_arm.c | 3 +- >> libavcodec/mlp.h | 10 +- >> libavcodec/mlp_parse.c | 31 ++- >> libavcodec/mlp_parse.h | 1 + >> libavcodec/mlp_parser.c | 11 +- >> libavcodec/mlpdec.c | 389 +++++++++++++++++++++++++++---- >> libavcodec/mlpdsp.c | 50 +++- >> libavcodec/mlpdsp.h | 25 ++ >> libavcodec/x86/mlpdsp.asm | 19 +- >> tests/fate/truehd.mak | 10 + >> 11 files changed, 476 insertions(+), 75 deletions(-) > > With atmos.thd i get: > >> [aist#0:0/truehd @ 00000209caf3ee00] Guessed Channel Layout: 7.1.4 >> Input #0, truehd, from '../samples/truehd/atmos.thd': >> Duration: N/A, start: 0.000000, bitrate: N/A >> Stream #0:0: Audio: truehd (Dolby TrueHD + Dolby Atmos), 48000 Hz, 7.1.4, >> s32 (24 bit) > > Which is unlikely to be correct. The file has 11 (or 12) objects, which is > exported as 12 channels in an unspecified layout, and automatically assumed > to be a 7.1.4 fixed layout. >
This is caused by `guess_input_channel_layout` (in `ffmpeg_demux.c`) which tries to assume a layout. Would using `AV_CHANNEL_ORDER_CUSTOM` with all channels set to `AV_CHAN_UNKNOWN` (for unknown position, except LFE if present) be a better solution? > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
