From: Paul B Mahol <onemda@gmail.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH] avfilter: add ambisonic decoder filter
Date: Sun, 30 Oct 2022 19:29:01 +0100
Message-ID: <CAPYw7P6HY9DqCLOAh=XiBGRFpcN6iauVFUJLrhd2B8XT8eq5aA@mail.gmail.com> (raw)
In-Reply-To: <3a38e8dc-0c3a-eec2-9278-75f2bc6118aa@gmail.com>
On 10/30/22, James Almer <jamrial@gmail.com> wrote:
>
>
> On 10/30/2022 3:19 PM, Paul B Mahol wrote:
>> On 10/30/22, James Almer <jamrial@gmail.com> wrote:
>>> On 10/30/2022 12:34 PM, Paul B Mahol wrote:
>>>> +static const struct {
>>>> + const int order;
>>>> + const int inputs;
>>>> + const int speakers;
>>>> + const int near_field;
>>>> + const int type;
>>>> + const double xover;
>>>> + const AVChannelLayout outlayout;
>>>> + const double *speakers_azimuth;
>>>> + const double *speakers_elevation;
>>>> + const double *speakers_distance;
>>>> +} ambisonic_tab[] = {
>>>> + [MONO] = {
>>>> + .order = 0,
>>>> + .inputs = 1,
>>>> + .speakers = 1,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO,
>>>> + .speakers_azimuth = (const double[1]){ 0. },
>>>> + .speakers_distance = (const double[1]){ 1. },
>>>> + },
>>>> + [STEREO] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 2,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO,
>>>> + .speakers_azimuth = (const double[2]){ -30, 30},
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [STEREO_DOWNMIX] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 2,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout =
>>>> (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO_DOWNMIX,
>>>> + .speakers_azimuth = (const double[2]){ -90, 90 },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [SURROUND] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 3,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_SURROUND,
>>>> + .speakers_azimuth = (const double[3]){ -45, 45, 0 },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [L2_1] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 3,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_2_1,
>>>> + .speakers_azimuth = (const double[3]){ -45, 45, 180 },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [TRIANGLE] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 3,
>>>> + .type = 1,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_SURROUND,
>>>> + .speakers_azimuth = (const double[3]){ -120, 120, 0 },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [QUAD] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 4,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_QUAD,
>>>> + .speakers_azimuth = (const double[4]){ -45, 45, -135, 135 },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [SQUARE] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 4,
>>>> + .type = 1,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_4POINT0,
>>>> + .speakers_azimuth = (const double[4]){ 0, -90, 180, 90 },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [L4_0] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 4,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_4POINT0,
>>>> + .speakers_azimuth = (const double[4]){ -30, 30, 0, 180 },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [L5_0] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 5,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_5POINT0_BACK,
>>>> + .speakers_azimuth = (const double[5]){ -30, 30, 0, -145, 145
>>>> },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [L5_0_SIDE] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 5,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_5POINT0,
>>>> + .speakers_azimuth = (const double[5]){ -30, 30, 0, -110, 110
>>>> },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [L6_0] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 6,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_6POINT0,
>>>> + .speakers_azimuth = (const double[6]){ -30, 30, 0, 180, -110,
>>>> 110
>>>> },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [L7_0] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 7,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_7POINT0,
>>>> + .speakers_azimuth = (const double[7]){ -30, 30, 0, -145, 145,
>>>> -110, 110 },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [TETRA] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 4,
>>>> + .type = 2,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_QUAD,
>>>> + .speakers_azimuth = (const double[4]){ -90, 90, 0, 180 },
>>>> + .speakers_elevation = (const double[4]){ -35.3, -35.3, 35.3,
>>>> 35.3
>>>> },
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>> + [CUBE] = {
>>>> + .order = 1,
>>>> + .inputs = 4,
>>>> + .speakers = 8,
>>>> + .type = 2,
>>>> + .near_field = NF_NONE,
>>>> + .xover = 0.,
>>>> + .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_7POINT1,
>>>
>>> 7.1 defines an LFE channel, which is clearly not intended here, so it
>>> should be either:
>>>
>>> .outlayout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MASK(8,
>>> AV_CH_LAYOUT_QUAD |
>>> AV_CH_TOP_FRONT_LEFT |
>>> AV_CH_TOP_FRONT_RIGHT |
>>> AV_CH_TOP_BACK_LEFT |
>>> AV_CH_TOP_BACK_RIGHT),
>>>
>>> Or the AV_CHANNEL_LAYOUT_CUBE layout (using the exact same bitmask as
>>> above) after the patch i sent just now is committed.
>>
>> CUBE is as real cube in 3d space. No current layout in API can be
>> described correctly.
>
> the TOP_* channels are in a different height layer than the other
> channels, namely above them. The result for this bitmask is a 3D cube
> layout (Left and right speakers both front and back, in two different
> height layers).
https://en.wikipedia.org/wiki/Ambisonic_reproduction_systems#Cube
>
>>
>>>
>>>> + .speakers_azimuth = cube_azimuth,
>>>> + .speakers_elevation = cube_elevation,
>>>> + .speakers_distance = same_distance,
>>>> + },
>>>
>>> _______________________________________________
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>>> ffmpeg-devel@ffmpeg.org
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>>>
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>>>
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next prev parent reply other threads:[~2022-10-30 18:29 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-30 15:34 Paul B Mahol
2022-10-30 16:15 ` James Almer
2022-10-30 18:19 ` Paul B Mahol
2022-10-30 18:24 ` James Almer
2022-10-30 18:29 ` Paul B Mahol [this message]
2022-10-30 18:55 ` James Almer
2022-10-30 18:58 ` Paul B Mahol
2022-10-30 19:14 ` James Almer
2022-10-30 19:19 ` Paul B Mahol
2022-10-30 19:41 ` James Almer
2022-10-30 19:59 ` James Almer
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