[FFmpeg-user] Decode ac3 from multichannel USB input
Fred Rotbart
rotbart at gmail.com
Sat Oct 28 15:36:46 EEST 2023
Here is one of my many other attempts. It should be clear that I am a
beginner with ffmpeg.
No matter what I try, ffmpeg seems to merge all the 32 USB channels into 6.
For example:
ffmpeg -ac 2 -c ac3 -loglevel debug -f avfoundation -i :2 -af 'pan=5.1'
output.wav
Part of the output:
Splitting the commandline.
Reading option '-ac' ... matched as option 'ac' (set number of audio
channels) with argument '2'.
Reading option '-c' ... matched as option 'c' (codec name) with argument
'ac3'.
Reading option '-loglevel' ... matched as option 'loglevel' (set logging
level) with argument 'debug'.
Reading option '-f' ... matched as option 'f' (force format) with
argument 'avfoundation'.
Reading option '-i' ... matched as input url with argument ':2'.
Reading option '-af' ... matched as option 'af' (set audio filters) with
argument 'pan=5.1'.
Reading option 'output.wav' ... matched as output url.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option loglevel (set logging level) with argument debug.
Successfully parsed a group of options.
Parsing a group of options: input url :2.
Applying option ac (set number of audio channels) with argument 2.
Applying option c (codec name) with argument ac3.
Applying option f (force format) with argument avfoundation.
Successfully parsed a group of options.
Opening an input file: :2.
[avfoundation @ 0x7f96400041c0] audio device 'Digiface USB (24162724)'
opened
For transform of length 128, inverse, mdct_float, flags: [aligned,
out_of_place], found 3 matches:
1: mdct_inv_float_avx2 - type: mdct_float, len: [16, ∞],
factors[2]: [2, any], flags: [aligned, out_of_place, inv_only], prio: 544
2: mdct_inv_float_c - type: mdct_float, len: [2, ∞], factors[2]:
[2, any], flags: [unaligned, out_of_place, inv_only], prio: 96
3: mdct_naive_inv_float_c - type: mdct_float, len: [2, ∞],
factors[2]: [2, any], flags: [unaligned, out_of_place, inv_only], prio:
-130976
For transform of length 64, inverse, fft_float, flags: [aligned,
inplace, preshuf, asm_call], found 3 matches:
1: fft_sr_asm_float_avx2 - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 480
2: fft_sr_asm_float_fma3 - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 448
3: fft_sr_asm_float_avx - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 416
Transform tree:
mdct_inv_float_avx2 - type: mdct_float, len: 128, factors[2]: [2,
any], flags: [aligned, out_of_place, inv_only]
fft_sr_asm_float_avx2 - type: fft_float, len: 64, factor: 2,
flags: [aligned, inplace, out_of_place, preshuf, asm_call]
For transform of length 256, inverse, mdct_float, flags: [aligned,
out_of_place], found 3 matches:
1: mdct_inv_float_avx2 - type: mdct_float, len: [16, ∞],
factors[2]: [2, any], flags: [aligned, out_of_place, inv_only], prio: 544
2: mdct_inv_float_c - type: mdct_float, len: [2, ∞], factors[2]:
[2, any], flags: [unaligned, out_of_place, inv_only], prio: 96
3: mdct_naive_inv_float_c - type: mdct_float, len: [2, ∞],
factors[2]: [2, any], flags: [unaligned, out_of_place, inv_only], prio:
-130976
For transform of length 128, inverse, fft_float, flags: [aligned,
inplace, preshuf, asm_call], found 3 matches:
1: fft_sr_asm_float_avx2 - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 480
2: fft_sr_asm_float_fma3 - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 448
3: fft_sr_asm_float_avx - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 416
Transform tree:
mdct_inv_float_avx2 - type: mdct_float, len: 256, factors[2]: [2,
any], flags: [aligned, out_of_place, inv_only]
fft_sr_asm_float_avx2 - type: fft_float, len: 128, factor: 2,
flags: [aligned, inplace, out_of_place, preshuf, asm_call]
[avfoundation @ 0x7f96400041c0] All info found
Input #0, avfoundation, from ':2':
Duration: N/A, start: 1307454.032041, bitrate: N/A
Stream #0:0, 1, 1/1000000: Audio: ac3, 44100 Hz, 32 channels, fltp
Successfully opened the file.
Parsing a group of options: output url output.wav.
Applying option af (set audio filters) with argument pan=5.1.
Successfully parsed a group of options.
Opening an output file: output.wav.
File 'output.wav' already exists. Overwrite? [y/N] y
[file @ 0x7f9640108000] Setting default whitelist 'file,crypto,data'
Successfully opened the file.
For transform of length 128, inverse, mdct_float, flags: [aligned,
out_of_place], found 3 matches:
1: mdct_inv_float_avx2 - type: mdct_float, len: [16, ∞],
factors[2]: [2, any], flags: [aligned, out_of_place, inv_only], prio: 544
2: mdct_inv_float_c - type: mdct_float, len: [2, ∞], factors[2]:
[2, any], flags: [unaligned, out_of_place, inv_only], prio: 96
3: mdct_naive_inv_float_c - type: mdct_float, len: [2, ∞],
factors[2]: [2, any], flags: [unaligned, out_of_place, inv_only], prio:
-130976
For transform of length 64, inverse, fft_float, flags: [aligned,
inplace, preshuf, asm_call], found 3 matches:
1: fft_sr_asm_float_avx2 - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 480
2: fft_sr_asm_float_fma3 - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 448
3: fft_sr_asm_float_avx - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 416
Transform tree:
mdct_inv_float_avx2 - type: mdct_float, len: 128, factors[2]: [2,
any], flags: [aligned, out_of_place, inv_only]
fft_sr_asm_float_avx2 - type: fft_float, len: 64, factor: 2,
flags: [aligned, inplace, out_of_place, preshuf, asm_call]
For transform of length 256, inverse, mdct_float, flags: [aligned,
out_of_place], found 3 matches:
1: mdct_inv_float_avx2 - type: mdct_float, len: [16, ∞],
factors[2]: [2, any], flags: [aligned, out_of_place, inv_only], prio: 544
2: mdct_inv_float_c - type: mdct_float, len: [2, ∞], factors[2]:
[2, any], flags: [unaligned, out_of_place, inv_only], prio: 96
3: mdct_naive_inv_float_c - type: mdct_float, len: [2, ∞],
factors[2]: [2, any], flags: [unaligned, out_of_place, inv_only], prio:
-130976
For transform of length 128, inverse, fft_float, flags: [aligned,
inplace, preshuf, asm_call], found 3 matches:
1: fft_sr_asm_float_avx2 - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 480
2: fft_sr_asm_float_fma3 - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 448
3: fft_sr_asm_float_avx - type: fft_float, len: [64, 131072],
factor: 2, flags: [aligned, inplace, out_of_place, preshuf, asm_call],
prio: 416
Transform tree:
mdct_inv_float_avx2 - type: mdct_float, len: 256, factors[2]: [2,
any], flags: [aligned, out_of_place, inv_only]
fft_sr_asm_float_avx2 - type: fft_float, len: 128, factor: 2,
flags: [aligned, inplace, out_of_place, preshuf, asm_call]
Stream mapping:
Stream #0:0 -> #0:0 (ac3 (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
[aost#0:0/pcm_s16le @ 0x7f963f745840] cur_dts is invalid [init:0
i_done:0 finish:0] (this is harmless if it occurs once at the start per
stream)
[AVFilterGraph @ 0x7fe03c4115c0] Setting 'args' to value '5.1'
detected 12 logical cores
[graph_0_in_0_0 @ 0x7fe03c4081c0] Setting 'time_base' to value '1/48000'
[graph_0_in_0_0 @ 0x7fe03c4081c0] Setting 'sample_rate' to value '48000'
[graph_0_in_0_0 @ 0x7fe03c4081c0] Setting 'sample_fmt' to value 'fltp'
[graph_0_in_0_0 @ 0x7fe03c4081c0] Setting 'channels' to value '32'
[graph_0_in_0_0 @ 0x7fe03c4081c0] tb:1/48000 samplefmt:fltp
samplerate:48000 chlayout:32 channels
[format_out_0_0 @ 0x7fe03c404200] Setting 'sample_fmts' to value 's16'
[format_out_0_0 @ 0x7fe03c404200] auto-inserting filter
'auto_aresample_0' between the filter 'Parsed_pan_0' and the filter
'format_out_0_0'
[AVFilterGraph @ 0x7fe03c4115c0] query_formats: 4 queried, 6 merged, 3
already done, 0 delayed
[Parsed_pan_0 @ 0x7fe03c40e180] [SWR @ 0x7fe040b00000] Using fltp
internally between filters
[Parsed_pan_0 @ 0x7fe03c40e180] o0 = 0 i0 + 0 i1 + 0 i2 + 0 i3 + 0 i4 +
0 i5 + 0 i6 + 0 i7 + 0 i8 + 0 i9 + 0 i10 + 0 i11 + 0 i12 + 0 i13 + 0 i14
+ 0 i15 + 0 i16 + 0 i17 + 0 i18 + 0 i19 + 0 i20 + 0 i21 + 0 i22 + 0 i23
+ 0 i24 + 0 i25 + 0 i26 + 0 i27 + 0 i28 + 0 i29 + 0 i30 + 0 i31
[Parsed_pan_0 @ 0x7fe03c40e180] o1 = 0 i0 + 0 i1 + 0 i2 + 0 i3 + 0 i4 +
0 i5 + 0 i6 + 0 i7 + 0 i8 + 0 i9 + 0 i10 + 0 i11 + 0 i12 + 0 i13 + 0 i14
+ 0 i15 + 0 i16 + 0 i17 + 0 i18 + 0 i19 + 0 i20 + 0 i21 + 0 i22 + 0 i23
+ 0 i24 + 0 i25 + 0 i26 + 0 i27 + 0 i28 + 0 i29 + 0 i30 + 0 i31
[Parsed_pan_0 @ 0x7fe03c40e180] o2 = 0 i0 + 0 i1 + 0 i2 + 0 i3 + 0 i4 +
0 i5 + 0 i6 + 0 i7 + 0 i8 + 0 i9 + 0 i10 + 0 i11 + 0 i12 + 0 i13 + 0 i14
+ 0 i15 + 0 i16 + 0 i17 + 0 i18 + 0 i19 + 0 i20 + 0 i21 + 0 i22 + 0 i23
+ 0 i24 + 0 i25 + 0 i26 + 0 i27 + 0 i28 + 0 i29 + 0 i30 + 0 i31
[Parsed_pan_0 @ 0x7fe03c40e180] o3 = 0 i0 + 0 i1 + 0 i2 + 0 i3 + 0 i4 +
0 i5 + 0 i6 + 0 i7 + 0 i8 + 0 i9 + 0 i10 + 0 i11 + 0 i12 + 0 i13 + 0 i14
+ 0 i15 + 0 i16 + 0 i17 + 0 i18 + 0 i19 + 0 i20 + 0 i21 + 0 i22 + 0 i23
+ 0 i24 + 0 i25 + 0 i26 + 0 i27 + 0 i28 + 0 i29 + 0 i30 + 0 i31
[Parsed_pan_0 @ 0x7fe03c40e180] o4 = 0 i0 + 0 i1 + 0 i2 + 0 i3 + 0 i4 +
0 i5 + 0 i6 + 0 i7 + 0 i8 + 0 i9 + 0 i10 + 0 i11 + 0 i12 + 0 i13 + 0 i14
+ 0 i15 + 0 i16 + 0 i17 + 0 i18 + 0 i19 + 0 i20 + 0 i21 + 0 i22 + 0 i23
+ 0 i24 + 0 i25 + 0 i26 + 0 i27 + 0 i28 + 0 i29 + 0 i30 + 0 i31
[Parsed_pan_0 @ 0x7fe03c40e180] o5 = 0 i0 + 0 i1 + 0 i2 + 0 i3 + 0 i4 +
0 i5 + 0 i6 + 0 i7 + 0 i8 + 0 i9 + 0 i10 + 0 i11 + 0 i12 + 0 i13 + 0 i14
+ 0 i15 + 0 i16 + 0 i17 + 0 i18 + 0 i19 + 0 i20 + 0 i21 + 0 i22 + 0 i23
+ 0 i24 + 0 i25 + 0 i26 + 0 i27 + 0 i28 + 0 i29 + 0 i30 + 0 i31
[Parsed_pan_0 @ 0x7fe03c40e180] Pure channel mapping detected: M M M M M M
[auto_aresample_0 @ 0x7fe03c40d280] [SWR @ 0x7fe03c72d000] Using fltp
internally between filters
[auto_aresample_0 @ 0x7fe03c40d280] ch:6 chl:5.1 fmt:fltp r:44100Hz ->
ch:6 chl:5.1 fmt:s16 r:48000Hz
Output #0, wav, to 'output.wav':
Metadata:
ISFT : Lavf60.3.100
Stream #0:0, 0, 1/48000: Audio: pcm_s16le ([1][0][0][0] /
0x0001), 48000 Hz, 5.1, s16, 4233 kb/s
Metadata:
encoder : Lavc60.3.100 pcm_s16le
[out#0/wav @ 0x7fe03b704840] All streams finished
[out#0/wav @ 0x7fe03b704840] Terminating muxer thread
I've read all the documentation and searched all the forums but could
not find anything that would give me a clue.
Please help.
- Fred
On 25/10/2023 14:00, Fred Rotbart wrote:
> Hi,
>
> I have a RME Digiface USB as input to my Mac. This has 32 SPDIF input
> channels, of which the first two have an ac3 signal and the others are
> not used.
> I have been trying to isolate and decode one of the ac3 channels to
> its six separate PCM channels but without success.
>
> For example, as one of the many attempts, I tried:
>
> ffmpeg -acodec ac3 -f avfoundation -capture_raw_data true -i :1 \
> -map_channel 0.0.0, \
> -af 'pan=5.1|c0=c0|c1=-|c2=FC|c3=LFE|c4=BL|c5=BR' \
> output.wav
>
> Can someone help me with this?
>
> - Fred
>
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