Ticket #1478 (closed defect: fixed)
PulseAudio input performance regression
|Reported by:||GreatEmerald||Owned by:|
|Blocking:||Reproduced by developer:||no|
|Analyzed by developer:||no|
Summary of the bug:
There has been a regression that severely reduces the performance of recording input PulseAudio streams using the pulse input device. Before the regression, I could record one audio and one video stream at a constant 30 frames per second (capped), but after the regression the recording keeps dropping frames, resulting in an unacceptable 25 FPS on average recording performance. It doesn't matter what video or audio codecs are in use, the result is always the same.
In order to identify where the problem lies, I used git bisect to see what was the regressing commit. Unfortunately, the last bisected commits didn't build properly (configure doesn't give me all of the options that I use for building a complete FFmpeg, and even with some of the options disabled, it only builds the libraries, and not the binary, which doesn't allow me to test whether the regression is still there or not). Still, bisecting allowed me to narrow down the list to these commits:
More precisely, commit 4778783160fb8d7aa39dafdabc756f1691b830f7 is the first confirmed bad commit, while commit dcd207c4cbcd9dd72b73e5b544c055b29885be64 was the last known good commit.
There is a non-ideal workaround for this regression, which is to switch to ALSA input rather than use the native PulseAudio one. However, that creates popping sounds in the recording.
I'm using openSUSE 12.1 x86_64, currently with PulseAudio 2.0, although before that I used PA 1.1. There is no change in performance between the two versions.
From the hardware side, I have two sound cards - a dedicated Creative SoundBlaster X-Fi XtremeGamer card, and an integrated Intel Azalia chip. Using either soundcard, recording an output monitor (system sounds) doesn't cause this problem, but recording an actual input device, such as a microphone, does.
How to reproduce:
To test this, I run FFmpeg like this:
/usr/bin/ffmpeg -xerror \ -f pulse -i alsa_input.pci-0000_00_14.2.analog-stereo \ -f x11grab -i :0.0 \ -codec:a pcm_s16le -threads 0 -y Video.mkv
The complete output of this command, using the last confirmed bad version, is as follows:
ffmpeg version N-39892-g4778783 Copyright (c) 2000-2012 the FFmpeg developers built on Jun 22 2012 18:44:00 with gcc 4.6.2 configuration: --shlibdir=/usr/lib64 --prefix=/usr --mandir=/usr/share/man --libdir=/usr/lib64 --enable-shared --disable-static --enable-debug --disable-stripping --extra-cflags='-fmessage-length=0 -O2 -march=native -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -g -fPIC -I/usr/include/gsm' --enable-gpl --enable-x11grab --enable-version3 --enable-pthreads --enable-avfilter --enable-libpulse libavutil 51. 46.100 / 51. 46.100 libavcodec 54. 14.101 / 54. 14.101 libavformat 54. 3.100 / 54. 3.100 libavdevice 53. 4.100 / 53. 4.100 libavfilter 2. 70.100 / 2. 70.100 libswscale 2. 1.100 / 2. 1.100 libswresample 0. 11.100 / 0. 11.100 libpostproc 52. 0.100 / 52. 0.100 Input #0, pulse, from 'alsa_input.pci-0000_00_14.2.analog-stereo': Duration: N/A, start: 0.634532, bitrate: N/A Stream #0:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s [x11grab @ 0x63a7c0] device: :0.0 -> display: :0.0 x: 0 y: 0 width: 640 height: 480 [x11grab @ 0x63a7c0] shared memory extension found Input #1, x11grab, from ':0.0': Duration: N/A, start: 1340381175.492614, bitrate: N/A Stream #1:0: Video: rawvideo (BGR / 0x524742), bgr0, 640x480, 294617 kb/s, 29.97 tbr, 1000k tbn, 29.97 tbc Incompatible pixel format 'bgr0' for codec 'mpeg4', auto-selecting format 'yuv420p' [buffer @ 0x639680] w:640 h:480 pixfmt:bgr0 tb:1/1000000 sar:0/1 sws_param:flags=2 [buffersink @ 0x641620] auto-inserting filter 'auto-inserted scale 0' between the filter 'src' and the filter 'out' [scale @ 0x641ec0] w:640 h:480 fmt:bgr0 sar:0/1 -> w:640 h:480 fmt:yuv420p sar:0/1 flags:0x4 Guessed Channel Layout for Input Stream #0.0 : stereo Output #0, matroska, to 'Video.mkv': Metadata: encoder : Lavf54.3.100 Stream #0:0: Video: mpeg4, yuv420p, 640x480, q=2-31, 200 kb/s, 1k tbn, 29.97 tbc Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s Stream mapping: Stream #1:0 -> #0:0 (rawvideo -> mpeg4) Stream #0:0 -> #0:1 (pcm_s16le -> pcm_s16le) Press [q] to stop, [?] for help frame= 264 fps= 24 q=25.8 Lsize= 2764kB time=00:00:10.98 bitrate=2061.9kbits/s dup=0 drop=27 video:687kB audio:2059kB global headers:0kB muxing overhead 0.625024%
- Keywords regression added
- Component changed from undetermined to FFmpeg