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Revolution of Open-source and film making towards open film making
6 octobre 2011, par
Mis à jour : Juillet 2013
Langue : English
Type : Texte
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Screen capture (video screencast) with FFMPEG with very low FPS
20 septembre 2023, par jesusdaI recently changed PCs, I went from having an Intel Core i5 4460 with integrated graphics card to a Xeon E5 2678 v3 with AMD RADEON RX 550 graphics.


On paper, the new PC is on the order of 3 to 7 times more powerful than the old one and I can attest that this is the case in daily use, video and image editing etc. The advantage of having so many cores and threads available is palpable. In terms of games I haven't tried it because I'm not really a gamer and the few games I use are the typical free ones that come with Debian and some emulators that, honestly, already worked fine with the old PC.


However there is one task that brings me head over heels for its terrible performance : video screen capture.


With my old PC I was able to capture at over 60 fps at full screen while doing any task I needed to record.


Even with my lenovo thinkpad x230 I am able to capture screen at over 80fps with total fluency.


The command I have always used is :


ffmpeg -f x11grab -draw_mouse 1 -framerate 60 -video_size 1920x1200 -i :0.0+1680,0 -qscale 0 -pix_fmt yuv420p -c:v libx264 -preset medium -qp 0 -q:v 1 -s 1920x1200 -f matroska -threads 4 video.mkv



notes :


-video_size 1920x1200 -i :0.0+1680,0 y -s 1920x1200
are the dimensions and position of the region to capture (my right monitor).

Notice that I even used
-preset medium
and software encoding, so I got very good quality even with that parameter setting and without ever going below 60 fps.

What happens to me now ?


The equipment is unable to capture more than 20 fps which makes any video invalid, with frame drops and not even reach 30fps, which would be the minimum required.


In addition, it is quite noticeable the decrease in responsiveness of the PC as soon as I launch the command. That is, all that fluidity and smoothness that is appreciated when working normally, disappears and even moving a window from one side to another is rough and stumbling.


I have tried with different parameters of ffmpeg, to capture raw, without encoding.


I have tried saving the resulting video directly to RAM disk in order to avoid the possible bottleneck of writing to disk. It doesn't affect it at all.


So, does anyone have any suggestions as to at least where I can dig further to find a solution to the problem ?


Additional data, in case it helps :


$ → inxi
CPU: 12-Core Intel Xeon E5-2678 v3 (-MT MCP-)
speed/min/max: 1201/1200/3300 MHz Kernel: 5.10.0-0.bpo.4-amd64 x86_64
Up: 1d 6h 55m Mem: 6427.6/32012.4 MiB (20.1%)
Storage: 13.76 TiB (55.9% used) Procs: 433 Shell: bash 5.0.18 inxi: 3.0.32


$ → ffmpeg -v
ffmpeg version 4.1.6 Copyright (c) 2000-2020 the FFmpeg developers
 built with gcc 8 (Debian 8.3.0-6)
 configuration: --disable-decoder=amrnb --disable-decoder=libopenjpeg --disable-libopencv --disable-outdev=sdl2 --disable-podpages --disable-sndio --disable-stripping --enable-libaom --enable-avfilter --enable-avresample --enable-gcrypt --disable-gnutls --enable-openssl --enable-gpl --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libfdk-aac --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libilbc --enable-libkvazaar --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx265 --enable-libzimg --enable-libxvid --enable-libzvbi --enable-nonfree --enable-opencl --enable-opengl --enable-postproc --enable-pthreads --enable-shared --enable-version3 --enable-libwebp --incdir=/usr/include/x86_64-linux-gnu --libdir=/usr/lib/x86_64-linux-gnu --prefix=/usr --toolchain=hardened --enable-frei0r --enable-chromaprint --enable-libx264 --enable-libiec61883 --enable-libdc1394 --enable-vaapi --enable-libmfx --enable-libvmaf --disable-altivec --shlibdir=/usr/lib/x86_64-linux-gnu
 libavutil 56. 22.100 / 56. 22.100
 libavcodec 58. 35.100 / 58. 35.100
 libavformat 58. 20.100 / 58. 20.100
 libavdevice 58. 5.100 / 58. 5.100
 libavfilter 7. 40.101 / 7. 40.101
 libavresample 4. 0. 0 / 4. 0. 0
 libswscale 5. 3.100 / 5. 3.100
 libswresample 3. 3.100 / 3. 3.100
 libpostproc 55. 3.100 / 55. 3.100



I have the free amdgpu drivers (not amdgpu-pro), but I activated OpenCL just in case.


I followed this tutorial.


$ → glxinfo | grep OpenGL
OpenGL vendor string: AMD
OpenGL renderer string: Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
OpenGL core profile version string: 4.6 (Core Profile) Mesa 20.3.4
OpenGL core profile shading language version string: 4.60
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 4.6 (Compatibility Profile) Mesa 20.3.4
OpenGL shading language version string: 4.60
OpenGL context flags: (none)
OpenGL profile mask: compatibility profile
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.2 Mesa 20.3.4
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20
OpenGL ES profile extensions:





$ → clinfo
Number of platforms 1
 Platform Name Clover
 Platform Vendor Mesa
 Platform Version OpenCL 1.1 Mesa 20.3.4
 Platform Profile FULL_PROFILE
 Platform Extensions cl_khr_icd
 Platform Extensions function suffix MESA

 Platform Name Clover
Number of devices 1
 Device Name Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
 Device Vendor AMD
 Device Vendor ID 0x1002
 Device Version OpenCL 1.1 Mesa 20.3.4
 Driver Version 20.3.4
 Device OpenCL C Version OpenCL C 1.1
 Device Type GPU
 Device Profile FULL_PROFILE
 Device Available Yes
 Compiler Available Yes
 Max compute units 8
 Max clock frequency 1183MHz
 Max work item dimensions 3
 Max work item sizes 256x256x256
 Max work group size 256
 Preferred work group size multiple 64
 Preferred / native vector sizes
 char 16 / 16
 short 8 / 8
 int 4 / 4
 long 2 / 2
 half 0 / 0 (n/a)
 float 4 / 4
 double 2 / 2 (cl_khr_fp64)
 Half-precision Floating-point support (n/a)
 Single-precision Floating-point support (core)
 Denormals No
 Infinity and NANs Yes
 Round to nearest Yes
 Round to zero No
 Round to infinity No
 IEEE754-2008 fused multiply-add No
 Support is emulated in software No
 Correctly-rounded divide and sqrt operations No
 Double-precision Floating-point support (cl_khr_fp64)
 Denormals Yes
 Infinity and NANs Yes
 Round to nearest Yes
 Round to zero Yes
 Round to infinity Yes
 IEEE754-2008 fused multiply-add Yes
 Support is emulated in software No
 Address bits 64, Little-Endian
 Global memory size 3221225472 (3GiB)
 Error Correction support No
 Max memory allocation 1717986918 (1.6GiB)
 Unified memory for Host and Device No
 Minimum alignment for any data type 128 bytes
 Alignment of base address 32768 bits (4096 bytes)
 Global Memory cache type None
 Image support No
 Local memory type Local
 Local memory size 32768 (32KiB)
 Max number of constant args 16
 Max constant buffer size 67108864 (64MiB)
 Max size of kernel argument 1024
 Queue properties
 Out-of-order execution No
 Profiling Yes
 Profiling timer resolution 0ns
 Execution capabilities
 Run OpenCL kernels Yes
 Run native kernels No
 Device Extensions cl_khr_byte_addressable_store cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_int64_base_atomics cl_khr_int64_extended_atomics cl_khr_fp64

NULL platform behavior
 clGetPlatformInfo(NULL, CL_PLATFORM_NAME, ...) Clover
 clGetDeviceIDs(NULL, CL_DEVICE_TYPE_ALL, ...) Success [MESA]
 clCreateContext(NULL, ...) [default] Success [MESA]
 clCreateContextFromType(NULL, CL_DEVICE_TYPE_DEFAULT) Success (1)
 Platform Name Clover
 Device Name Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
 clCreateContextFromType(NULL, CL_DEVICE_TYPE_CPU) No devices found in platform
 clCreateContextFromType(NULL, CL_DEVICE_TYPE_GPU) Success (1)
 Platform Name Clover
 Device Name Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
 clCreateContextFromType(NULL, CL_DEVICE_TYPE_ACCELERATOR) No devices found in platform
 clCreateContextFromType(NULL, CL_DEVICE_TYPE_CUSTOM) No devices found in platform
 clCreateContextFromType(NULL, CL_DEVICE_TYPE_ALL) Success (1)
 Platform Name Clover
 Device Name Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)

ICD loader properties
 ICD loader Name OpenCL ICD Loader
 ICD loader Vendor OCL Icd free software
 ICD loader Version 2.2.12
 ICD loader Profile OpenCL 2.2



This would not be a tearing problem, as no tearing is visible when playing videos and the TearFree driver policy is enabled.


$ → xrandr --verbose | grep TearFree
 TearFree: on
 TearFree: on
 TearFree: on



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ffmpeg rtmp webcam live stream iphone/pad segment size too big
1er février 2013, par Foo BarazzI'm transcoding a rtmp stream from a red5 server for use to live stream on a iphone or ipad device. I built latest ffmpeg version from git repo using the built in segmenter to create .ts files and m3u8 playlist file using the following :
ffmpeg -probesize 50k -i "rtmp://localhost/oflaDemo/red5StreamDemo live=1" \
-c:v libx264 -b:v 128k -vpre ipod320 -flags -global_header -map 0 \
-f segment -segment_time 3 -segment_list foo.m3u8 -segment_list_flags +live \
-segment_list_type m3u8 -segment_list_size 5 -segment_format mpegts foo%d.tsThis works fine, but I can't get the segment size smaller than about 12 sec even set to 3 (-segment_time 3). It seems to be caused by libx264 vcodec.
Am I missing any flag ?By the way, you can simple run the ffmpeg command above successfully by starting red5 SimpleBroadcaster example.
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How to compile ffmpeg for an iphone application
27 décembre 2012, par SwatiI am trying to compile ffmpeg for my iphone app so that i can
convert amr file to mp3
I downloaded latest version of ffmpeg and tried to configure it via terminal on my mac.
but i couldn't succeed, it always shows numerous errors :
cannot find make command
/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc is unable to create an executable file.
libavcodec.a file not found
libavfilter.a file not found
libavutil.a file not found
libswscale.a file not found
libavdevice.a file not found
libavformat.a file not found
libswresample.a file not foundi tried following links :
FFmpeg on iPhoneUsing FFMPEG library with iPhone SDK for video encoding
and many more...
could not fins step by step instructions..
Hope somebody can guide me with ffmpeg config