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Old 9th April 2018, 19:20   #22  |  Link
hello_hello
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Join Date: Mar 2011
Posts: 4,823
To make it even more interesting, ffmpeg changes downmix coefficients according to the output format.

-report -loglevel debug -i - -ignore_length true -ac 2 -c:a aac %d

32 bit float:

Quote:
Stream mapping:
Stream #0:0 -> #0:0 (pcm_f32le (native) -> aac (native))
cur_dts is invalid (this is harmless if it occurs once at the start per stream)
detected 4 logical cores
[graph_0_in_0_0 @ 039aad00] Setting 'time_base' to value '1/48000'
[graph_0_in_0_0 @ 039aad00] Setting 'sample_rate' to value '48000'
[graph_0_in_0_0 @ 039aad00] Setting 'sample_fmt' to value 'flt'
[graph_0_in_0_0 @ 039aad00] Setting 'channel_layout' to value '0x3f'
[graph_0_in_0_0 @ 039aad00] tb:1/48000 samplefmt:flt samplerate:48000 chlayout:0x3f
[format_out_0_0 @ 039abe80] Setting 'sample_fmts' to value 'fltp'
[format_out_0_0 @ 039abe80] Setting 'sample_rates' to value '96000|88200|64000|48000|44100|32000|24000|22050|16000|12000|11025|8000|7350'
[format_out_0_0 @ 039abe80] Setting 'channel_layouts' to value '0x3'
[format_out_0_0 @ 039abe80] auto-inserting filter 'auto_resampler_0' between the filter 'Parsed_anull_0' and the filter 'format_out_0_0'
[AVFilterGraph @ 039aa180] query_formats: 4 queried, 6 merged, 3 already done, 0 delayed
[auto_resampler_0 @ 039ac8c0] [SWR @ 039acf80] Using fltp internally between filters
[auto_resampler_0 @ 039ac8c0] [SWR @ 039acf80] Matrix coefficients:
[auto_resampler_0 @ 039ac8c0] [SWR @ 039acf80] FL: FL:1.000000 FR:0.000000 FC:0.707107 LFE:0.000000 BL:0.707107 BR:0.000000
[auto_resampler_0 @ 039ac8c0] [SWR @ 039acf80] FR: FL:0.000000 FR:1.000000 FC:0.707107 LFE:0.000000 BL:0.000000 BR:0.707107

[auto_resampler_0 @ 039ac8c0] ch:6 chl:5.1 fmt:flt r:48000Hz -> ch:2 chl:stereo fmt:fltp r:48000Hz
Output #0, ipod, to 'test.m4a':
Metadata:
encoder : Lavf58.9.100
Stream #0:0, 0, 1/48000: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, delay 1024, 128 kb/s
Metadata:
encoder : Lavc58.11.101 aac
24 bit integer:

Quote:
Stream mapping:
Stream #0:0 -> #0:0 (pcm_s24le (native) -> aac (native))
cur_dts is invalid (this is harmless if it occurs once at the start per stream)
detected 4 logical cores
[graph_0_in_0_0 @ 039ab4c0] Setting 'time_base' to value '1/48000'
[graph_0_in_0_0 @ 039ab4c0] Setting 'sample_rate' to value '48000'
[graph_0_in_0_0 @ 039ab4c0] Setting 'sample_fmt' to value 's32'
[graph_0_in_0_0 @ 039ab4c0] Setting 'channel_layout' to value '0x3f'
[graph_0_in_0_0 @ 039ab4c0] tb:1/48000 samplefmt:s32 samplerate:48000 chlayout:0x3f
[format_out_0_0 @ 039ac100] Setting 'sample_fmts' to value 'fltp'
[format_out_0_0 @ 039ac100] Setting 'sample_rates' to value '96000|88200|64000|48000|44100|32000|24000|22050|16000|12000|11025|8000|7350'
[format_out_0_0 @ 039ac100] Setting 'channel_layouts' to value '0x3'
[format_out_0_0 @ 039ac100] auto-inserting filter 'auto_resampler_0' between the filter 'Parsed_anull_0' and the filter 'format_out_0_0'
[AVFilterGraph @ 039aa980] query_formats: 4 queried, 6 merged, 3 already done, 0 delayed
[auto_resampler_0 @ 039ad080] [SWR @ 039ad740] Using fltp internally between filters
[auto_resampler_0 @ 039ad080] [SWR @ 039ad740] Matrix coefficients:
[auto_resampler_0 @ 039ad080] [SWR @ 039ad740] FL: FL:1.000000 FR:0.000000 FC:0.707107 LFE:0.000000 BL:0.707107 BR:0.000000
[auto_resampler_0 @ 039ad080] [SWR @ 039ad740] FR: FL:0.000000 FR:1.000000 FC:0.707107 LFE:0.000000 BL:0.000000 BR:0.707107

[auto_resampler_0 @ 039ad080] ch:6 chl:5.1 fmt:s32 r:48000Hz -> ch:2 chl:stereo fmt:fltp r:48000Hz
Output #0, ipod, to 'test.m4a':
Metadata:
encoder : Lavf58.9.100
Stream #0:0, 0, 1/48000: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp (24 bit), delay 1024, 128 kb/s
Metadata:
encoder : Lavc58.11.101 aac
16 bit integer:

Quote:
Stream mapping:
Stream #0:0 -> #0:0 (pcm_s16le (native) -> aac (native))
cur_dts is invalid (this is harmless if it occurs once at the start per stream)
detected 4 logical cores
[graph_0_in_0_0 @ 0399e880] Setting 'time_base' to value '1/48000'
[graph_0_in_0_0 @ 0399e880] Setting 'sample_rate' to value '48000'
[graph_0_in_0_0 @ 0399e880] Setting 'sample_fmt' to value 's16'
[graph_0_in_0_0 @ 0399e880] Setting 'channel_layout' to value '0x3f'
[graph_0_in_0_0 @ 0399e880] tb:1/48000 samplefmt:s16 samplerate:48000 chlayout:0x3f
[format_out_0_0 @ 03af3a80] Setting 'sample_fmts' to value 'fltp'
[format_out_0_0 @ 03af3a80] Setting 'sample_rates' to value '96000|88200|64000|48000|44100|32000|24000|22050|16000|12000|11025|8000|7350'
[format_out_0_0 @ 03af3a80] Setting 'channel_layouts' to value '0x3'
[format_out_0_0 @ 03af3a80] auto-inserting filter 'auto_resampler_0' between the filter 'Parsed_anull_0' and the filter 'format_out_0_0'
[AVFilterGraph @ 03920f80] query_formats: 4 queried, 6 merged, 3 already done, 0 delayed
[auto_resampler_0 @ 03985580] [SWR @ 03a4f240] Using fltp internally between filters
[auto_resampler_0 @ 03985580] [SWR @ 03a4f240] Matrix coefficients:
[auto_resampler_0 @ 03985580] [SWR @ 03a4f240] FL: FL:1.000000 FR:0.000000 FC:0.707107 LFE:0.000000 BL:0.707107 BR:0.000000
[auto_resampler_0 @ 03985580] [SWR @ 03a4f240] FR: FL:0.000000 FR:1.000000 FC:0.707107 LFE:0.000000 BL:0.000000 BR:0.707107

[auto_resampler_0 @ 03985580] ch:6 chl:5.1 fmt:s16 r:48000Hz -> ch:2 chl:stereo fmt:fltp r:48000Hz
Output #0, ipod, to 'test.m4a':
Metadata:
encoder : Lavf58.9.100
Stream #0:0, 0, 1/48000: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, delay 1024, 128 kb/s
Metadata:
encoder : Lavc58.11.101 aac

Last edited by hello_hello; 9th April 2018 at 19:35.
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