| Message ID | 20200729113952.14574-1-jeebjp@gmail.com |
|---|---|
| Headers | show |
| Series | 22.2 channel layout support for AAC decoding | expand |
On Wed, Jul 29, 2020 at 2:39 PM Jan Ekström <jeebjp@gmail.com> wrote: > > swresample seems to give out the correct channels for 5.1 and stereo > downmix (checked with ffmpeg.c by utilizing `-channel_layout` 5.1 and stereo), > although the default downmix logic seems to lower the volume somewhat. > I attempted to take this into mention, and apparently seem to have succeeded. Not pretty but since we don't yet have a full matrix for it and as the rest of the channel layout doesn't follow the bit mask's rising order I guess for now this is the least bad way of handling it. Added a warning since anyone interested in actually implementing this in a more complete manner might get interested. Note: I have no idea if this is the correct location or way to put this override, but since the stereo overrides seemed to be here as well, I followed similar logic. format-patch follows: From 16e9eda23862daaaf2a43824b75ddf7e8054f23e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jan=20Ekstr=C3=B6m?= <jeebjp@gmail.com> Date: Thu, 30 Jul 2020 23:52:57 +0300 Subject: [PATCH] swresample/rematrix: treat 22.2 as 5.1 (back) when mixing Only this sub-set of channels actually follows the bit mask order in the official 22.2 channel mapping. --- libswresample/rematrix.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/libswresample/rematrix.c b/libswresample/rematrix.c index 6b5feaa07b..43845a429f 100644 --- a/libswresample/rematrix.c +++ b/libswresample/rematrix.c @@ -141,6 +141,16 @@ av_cold int swr_build_matrix(uint64_t in_ch_layout_param, uint64_t out_ch_layout ) in_ch_layout = AV_CH_LAYOUT_STEREO; + if (in_ch_layout_param == AV_CH_LAYOUT_22POINT2 && + out_ch_layout_param != AV_CH_LAYOUT_22POINT2) { + in_ch_layout = AV_CH_LAYOUT_5POINT1_BACK; + av_get_channel_layout_string(buf, sizeof(buf), -1, in_ch_layout); + av_log(log_context, AV_LOG_WARNING, + "Full-on remixing from 22.2 has not yet been implemented! " + "Processing the input as '%s'\n", + buf); + } + if(!sane_layout(in_ch_layout)){ av_get_channel_layout_string(buf, sizeof(buf), -1, in_ch_layout_param); av_log(log_context, AV_LOG_ERROR, "Input channel layout '%s' is not supported\n", buf);
Now that we actually have sample(s) for channel_config 13, it was possible to see at which various points the AAC decoder fails attempting to parse the bit stream. As the feature `-request_channel_layout 9223372036854775808` (AV_CH_LAYOUT_NATIVE) seems to work, the channel order has been validated both visually with Audacity, as well as by logging the post-reorder element ordering: (what specific CPE/SCE/LFE elements mean is documented in the `avcodec/aacdectab: add mapping for 22.2` commit): Setting layout map list after reorder... tag 0 = { pos: (null) (3), syn_elem: CPE, elem_id: 1 } tag 1 = { pos: FC (4), syn_elem: SCE, elem_id: 0 } tag 2 = { pos: LFE (8), syn_elem: LFE, elem_id: 0 } tag 3 = { pos: (null) (30), syn_elem: CPE, elem_id: 3 } tag 4 = { pos: (null) (c0), syn_elem: CPE, elem_id: 0 } tag 5 = { pos: BC (100), syn_elem: SCE, elem_id: 1 } tag 6 = { pos: LFE2 (800000000), syn_elem: LFE, elem_id: 1 } tag 7 = { pos: (null) (600), syn_elem: CPE, elem_id: 2 } tag 8 = { pos: (null) (5000), syn_elem: CPE, elem_id: 4 } tag 9 = { pos: TFC (2000), syn_elem: SCE, elem_id: 2 } tag 10 = { pos: TC (800), syn_elem: SCE, elem_id: 3 } tag 11 = { pos: (null) (28000), syn_elem: CPE, elem_id: 6 } tag 12 = { pos: (null) (3000000000), syn_elem: CPE, elem_id: 5 } tag 13 = { pos: TBC (10000), syn_elem: SCE, elem_id: 4 } tag 14 = { pos: BFC (8000000000), syn_elem: SCE, elem_id: 5 } tag 15 = { pos: (null) (14000000000), syn_elem: CPE, elem_id: 7 } swresample seems to give out the correct channels for 5.1 and stereo downmix (checked with ffmpeg.c by utilizing `-channel_layout` 5.1 and stereo), although the default downmix logic seems to lower the volume somewhat. Fixes #8714 Jan Ekström (5): avutil/channel_layout: add 22.2 layout avcodec/mpeg4audio: add newer channel_coding mappings avcodec/aacdectab: add mapping for 22.2 avcodec/aacdec_template: mark second LFE element as LFE2 avcodec/aacdec_template: add support for 22.2 / channel_config 13 doc/APIchanges | 5 ++ libavcodec/aacdec_template.c | 98 ++++++++++++++++++++++++++++++++---- libavcodec/aacdectab.h | 23 ++++++++- libavcodec/mpeg4audio.c | 17 ++++++- libavcodec/mpeg4audio.h | 2 +- libavutil/channel_layout.c | 6 +++ libavutil/channel_layout.h | 6 +++ libavutil/version.h | 2 +- 8 files changed, 142 insertions(+), 17 deletions(-)