On Sat, Apr 9, 2022 at 5:22 PM morgan holly via ffmpeg-user < [email protected]> wrote:
> this is part question and part warning. When I run the cmd below FFMPEG > automatically knocks my 24bit source audio down to 8bits(!). I was able to > change that by adding 'aformat=sample_fmts=s32' into the filterchain for > the anullsrc inputs. > > The warning is: make sure you check your output quality if you use lavfi > slugs with your audio. 24->8bits, yikes. > > The question is: Can I specify the format of the nullsource when using > lavfi. Seems dangerous that it defaults to fmt:u8. Am I doing something > wrong? > You are not setting aformat right after anullsrc filter. > > Here is the spot in the log where it reports the bit depth change (log > level 48): > [format_out_0_0 @ 0x134709b60] auto-inserting filter 'auto_resampler_1' > between the filter 'Parsed_concat_0' and the filter 'format_out_0_0' > [AVFilterGraph @ 0x1347084b0] query_formats: 9 queried, 18 merged, 6 > already done, 0 delayed > [auto_resampler_0 @ 0x134606c70] [SWR @ 0x118008000] Using fltp internally > between filters > [auto_resampler_0 @ 0x134606c70] [SWR @ 0x118008000] Treating 1 channels > (FL) as mono > [auto_resampler_0 @ 0x134606c70] [SWR @ 0x118008000] Matrix coefficients: > [auto_resampler_0 @ 0x134606c70] [SWR @ 0x118008000] FC: FC:1.000000 > [auto_resampler_0 @ 0x134606c70] ch:1 chl:1 channels (FL) fmt:s32 > r:48000Hz -> ch:1 chl:mono fmt:u8 r:48000Hz > > Here is the ffmpeg cmd (16bit wav output): > ffmpeg -loglevel 48 -y -f lavfi -t 1.724 -i > anullsrc=channel_layout=mono:sample_rate=48000 -ss 120 -t 30.327979 -i > /tmp/2ch.mov -f lavfi -t 1.724 -i > anullsrc=channel_layout=mono:sample_rate=48000 -filter_complex > "[0:a:0][1:a:0][2:a:0]concat=n=3:v=0:a=1[sf1_out]" -map [sf1_out] > /tmp/noisetest.wav > > Here is the cmd line output: > ffmpeg version 4.4.1 Copyright (c) 2000-2021 the FFmpeg developers > built with Apple clang version 13.1.6 (clang-1316.0.21.2) > configuration: > libavutil 56. 70.100 / 56. 70.100 > libavcodec 58.134.100 / 58.134.100 > libavformat 58. 76.100 / 58. 76.100 > libavdevice 58. 13.100 / 58. 13.100 > libavfilter 7.110.100 / 7.110.100 > libswscale 5. 9.100 / 5. 9.100 > libswresample 3. 9.100 / 3. 9.100 > Input #0, lavfi, from 'anullsrc=channel_layout=mono:sample_rate=48000': > Duration: N/A, start: 0.000000, bitrate: 384 kb/s > Stream #0:0: Audio: pcm_u8, 48000 Hz, mono, u8, 384 kb/s > Input #1, mov,mp4,m4a,3gp,3g2,mj2, from '/tmp/2ch.mov': > Metadata: > major_brand : qt > minor_version : 537199360 > compatible_brands: qt > creation_time : 2016-07-11T16:36:32.000000Z > com.apple.quicktime.player.movie.audio.gain: 1.000000 > com.apple.quicktime.player.movie.audio.treble: 0.000000 > com.apple.quicktime.player.movie.audio.bass: 0.000000 > com.apple.quicktime.player.movie.audio.balance: 0.000000 > com.apple.quicktime.player.movie.audio.pitchshift: 0.000000 > com.apple.quicktime.player.movie.audio.mute: > com.apple.quicktime.player.version: 7.6.6 (7.6.6) > com.apple.quicktime.version: 7.7.3 (2890.9) 0x7738000 (Mac OS X, > 10.10.5, 14F1605) > timecode : 00:00:00:00 > Duration: 00:52:43.08, start: 0.000000, bitrate: 2304 kb/s > Stream #1:0(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, 1 > channels (FL), s32 (24 bit), 1152 kb/s (default) > Metadata: > creation_time : 2016-07-11T16:36:32.000000Z > handler_name : Apple Sound Media Handler > vendor_id : [0][0][0][0] > Stream #1:1(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, 1 > channels (FR), s32 (24 bit), 1152 kb/s (default) > Metadata: > creation_time : 2016-07-11T16:36:32.000000Z > handler_name : Apple Sound Media Handler > vendor_id : [0][0][0][0] > Stream #1:2(eng): Data: none (tmcd / 0x64636D74) (default) > Metadata: > creation_time : 2016-07-11T16:36:32.000000Z > handler_name : Time Code Media Handler > reel_name : TEST > timecode : 00:00:00:00 > Input #2, lavfi, from 'anullsrc=channel_layout=mono:sample_rate=48000': > Duration: N/A, start: 0.000000, bitrate: 384 kb/s > Stream #2:0: Audio: pcm_u8, 48000 Hz, mono, u8, 384 kb/s > Stream mapping: > Stream #0:0 (pcm_u8) -> concat:in0:a0 > Stream #1:0 (pcm_s24le) -> concat:in1:a0 > Stream #2:0 (pcm_u8) -> concat:in2:a0 > concat -> Stream #0:0 (pcm_s16le) > Press [q] to stop, [?] for help > Output #0, wav, to '/tmp/noisetest.wav': > Metadata: > ISFT : Lavf58.76.100 > Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, mono, > s16, 768 kb/s (default) > Metadata: > encoder : Lavc58.134.100 pcm_s16le > > > Thanks! > _______________________________________________ > ffmpeg-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". > _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
