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• libvlc ffmpeg : No seek in mpegts h264 stream

  26 juillet 2016, par ElDorado

  I am using ffmpeg to record video input from GDI (windows screen recorder) to view it later using VLC (via ActiveX plugin) + ffmpeg to decode it.

  Right now seeking in video is not working in VLC via plugin (which is critical). VLC player itself provide seeking, but it is more like byte position seeking (on I- frames which are larger than other frames it makes larger steps on horizontal scroll and also there are no timestamps).

  Encoder is opened with next defaults :

  avformat_alloc_output_context2(&outputContext, NULL, "mpegts", "test.mpg");
  
  outputFormat = outputContext->oformat;
  
  encoder = avcodec_find_encoder(AV_CODEC_ID_H264);
  
  outputStream = avformat_new_stream(outputContext, encoder);
  
  outputStream->id = outputContext->nb_streams - 1;
  
  encoderContext = outputStream->codec;
  
  encoderContext->bit_rate = bitrate;   // 800000 by default
  
  encoderContext->rc_max_rate = bitrate;
  
  encoderContext->width = imageWidth;   // 1920
  
  encoderContext->height = imageHeight; // 1080
  
  encoderContext->time_base.num = 1;
  
  encoderContext->time_base.den = fps;  // 25 by default
  
  encoderContext->gop_size = fps;
  
  encoderContext->keyint_min = fps;
  
  encoderContext->max_b_frames = 0;
  
  encoderContext->pix_fmt = AV_PIX_FMT_YUV420P;
  
  outputStream->time_base = encoderContext->time_base;
  
  avcodec_open2(encoderContext, encoder, NULL);

  Recording is done this way :

  // my impl of GDI recorder, returning AVFrame with only data and linesize filled.
  
  AVFrame* tmp_frame = impl_->recorder->acquireFrame();
  
  
  
  // converting RGB -> YUV420
  
  sws_scale(impl_->scaleContext, tmp_frame->data, tmp_frame->linesize, 0, impl_->frame->height, impl_->frame->data, impl_->frame->linesize);
  
  
  
  // pts variable is calculated by using QueryPerformanceCounter form WinAPI. It is strictly increasing
  
  impl_->frame->pts = pts;
  
  
  
  avcodec_encode_video2(impl_->encoderContext, impl_->packet, impl_->frame, &out_size);
  
  
  
  if (out_size) {
  
       impl_->packet->pts = pts;
  
       impl_->packet->dts = pts;
  
       impl_->packet->duration = 1; // here it is! It is set but has no effect
  
       av_packet_rescale_ts(impl_->packet, impl_->encoderContext->time_base, impl_->outputStream->time_base);
  
       // here pts = 3600*pts, dts = 3600*pts, duration = 3600 what I consider to be legit in terms of milliseconds
  
       impl_->packet->stream_index = impl_->outputStream->index;
  
       av_interleaved_write_frame(impl_->outputContext, impl_->packet);
  
       av_packet_unref(impl_->packet);
  
       out_size = 0;
  
  }

  ffprobe is providing next info on frames :

  [FRAME]
  
  media_type=video
  
  stream_index=0
  
  key_frame=1
  
  pkt_pts=3600
  
  pkt_pts_time=0:00:00.040000
  
  pkt_dts=3600
  
  pkt_dts_time=0:00:00.040000
  
  best_effort_timestamp=3600
  
  best_effort_timestamp_time=0:00:00.040000
  
  pkt_duration=N/A
  
  pkt_duration_time=N/A
  
  pkt_pos=564
  
  pkt_size=97.018555 Kibyte
  
  width=1920
  
  height=1080
  
  pix_fmt=yuv420p
  
  sample_aspect_ratio=N/A
  
  pict_type=I
  
  coded_picture_number=0
  
  display_picture_number=0
  
  interlaced_frame=0
  
  top_field_first=0
  
  repeat_pict=0
  
  [/FRAME]

  I believe that problem is in pkt_duration variable, though it was set.
  What I am doing wrong in recording so I can’t seek in video ?

  P.S. on other videos (also h264) seeking is working in ActiveX VLC plugin.

• Add padding with ffmpeg to videos increases file size, why ?

  12 mars 2023, par try2getsmarter

  I need to add padding to mp4 video files (since tv changes aspect ratio on playback) and I simply can do this with -pad option of ffmpeg.

  


  The output is ok for me, but I see that most of the video files increase about 25%-30% in file size.

  


  ffmpeg -i in.mp4 -preset slow -vf "pad=1920:1080 :(1920-iwmin(1920/iw,1080/ih))/2 :(1080-ihmin(1920/iw,1080/ih))/2" -c:v h264 -c:a copy out_fhd.mp4"

  


  Is there a way to preserve the input quality and have the same file size ? As the black bars contain no information I had the expectation that there is a lossless mode to take the already H264 encoded stream and just add blocks with black pixels.

  


• VideoWriter Doesn't work using openCV, ubuntu, Qt

  25 janvier 2023, par underflow223

  My code :

  


  cv::VideoWriter(
  strFile.toStdString(),
  cv::VideoWriter::fourcc('m','p','4','v'),
  nfps,
  cv::Size(1920/nresize, 1080/nresize)
);


  


  Error message :

  


  [mpeg4_v4l2m2m @ 0x7f50a43c50] arm_release_ver of this libmali is 'g6p0-01eac0', rk_so_ver is '7'.
Could not find a valid device
[mpeg4_v4l2m2m @ 0x7f50a43c50] can't configure encoder


  


  If I use MJPG codec, it works fine thow.

  


  This is OPENCV configure info :

  


  -- General configuration for OpenCV 4.6.0 =====================================
--   Version control:               unknown
-- 
--   Extra modules:
--     Location (extra):            /home/firefly/Downloads/opencv_contrib-4.6.0/modules
--     Version control (extra):     unknown
-- 
--   Platform:
--     Timestamp:                   2023-01-19T02:11:26Z
--     Host:                        Linux 5.10.110 aarch64
--     CMake:                       3.16.3
--     CMake generator:             Unix Makefiles
--     CMake build tool:            /usr/bin/make
--     Configuration:               Release
-- 
--   CPU/HW features:
--     Baseline:                    NEON FP16
-- 
--   C/C++:
--     Built as dynamic libs?:      YES
--     C++ standard:                11
--     C++ Compiler:                /usr/bin/c++  (ver 9.4.0)
--     C++ flags (Release):         -fsigned-char -W -Wall -Wreturn-type -Wnon-virtual-dtor -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Wsuggest-override -Wno-delete-non-virtual-dtor -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG  -DNDEBUG
--     C++ flags (Debug):           -fsigned-char -W -Wall -Wreturn-type -Wnon-virtual-dtor -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Wsuggest-override -Wno-delete-non-virtual-dtor -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -fvisibility-inlines-hidden -g  -O0 -DDEBUG -D_DEBUG
--     C Compiler:                  /usr/bin/cc
--     C flags (Release):           -fsigned-char -W -Wall -Wreturn-type -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -O3 -DNDEBUG  -DNDEBUG
--     C flags (Debug):             -fsigned-char -W -Wall -Wreturn-type -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -g  -O0 -DDEBUG -D_DEBUG
--     Linker flags (Release):      -Wl,--gc-sections -Wl,--as-needed -Wl,--no-undefined  
--     Linker flags (Debug):        -Wl,--gc-sections -Wl,--as-needed -Wl,--no-undefined  
--     ccache:                      NO
--     Precompiled headers:         NO
--     Extra dependencies:          dl m pthread rt
--     3rdparty dependencies:
-- 
--   OpenCV modules:
--     To be built:                 aruco barcode bgsegm bioinspired calib3d ccalib core datasets dnn dnn_objdetect dnn_superres dpm face features2d flann freetype fuzzy gapi hfs highgui img_hash imgcodecs imgproc intensity_transform line_descriptor mcc ml objdetect optflow phase_unwrapping photo plot quality rapid reg rgbd saliency shape stereo stitching structured_light superres surface_matching text tracking ts video videoio videostab wechat_qrcode xfeatures2d ximgproc xobjdetect xphoto
--     Disabled:                    world
--     Disabled by dependency:      -
--     Unavailable:                 alphamat cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev cvv hdf java julia matlab ovis python2 python3 sfm viz
--     Applications:                tests perf_tests apps
--     Documentation:               NO
--     Non-free algorithms:         NO
-- 
--   GUI:                           GTK3
--     GTK+:                        YES (ver 3.24.20)
--       GThread :                  YES (ver 2.64.6)
--       GtkGlExt:                  NO
--     VTK support:                 NO
-- 
--   Media I/O: 
--     ZLib:                        /usr/lib/aarch64-linux-gnu/libz.so (ver 1.2.11)
--     JPEG:                        /usr/lib/aarch64-linux-gnu/libjpeg.so (ver 80)
--     WEBP:                        build (ver encoder: 0x020f)
--     PNG:                         /usr/lib/aarch64-linux-gnu/libpng.so (ver 1.6.37)
--     TIFF:                        /usr/lib/aarch64-linux-gnu/libtiff.so (ver 42 / 4.1.0)
--     JPEG 2000:                   build (ver 2.4.0)
--     OpenEXR:                     build (ver 2.3.0)
--     HDR:                         YES
--     SUNRASTER:                   YES
--     PXM:                         YES
--     PFM:                         YES
-- 
--   Video I/O:
--     DC1394:                      YES (2.2.5)
--     FFMPEG:                      YES
--       avcodec:                   YES (58.54.100)
--       avformat:                  YES (58.29.100)
--       avutil:                    YES (56.31.100)
--       swscale:                   YES (5.5.100)
--       avresample:                YES (4.0.0)
--     GStreamer:                   YES (1.16.2)
--     v4l/v4l2:                    YES (linux/videodev2.h)
-- 
--   Parallel framework:            pthreads
-- 
--   Trace:                         YES (with Intel ITT)
-- 
--   Other third-party libraries:
--     Lapack:                      NO
--     Eigen:                       NO
--     Custom HAL:                  YES (carotene (ver 0.0.1))
--     Protobuf:                    build (3.19.1)
-- 
--   OpenCL:                        YES (no extra features)
--     Include path:                /home/firefly/Downloads/opencv-4.6.0/3rdparty/include/opencl/1.2
--     Link libraries:              Dynamic load
-- 
--   Python (for build):            /usr/bin/python2.7
-- 
--   Java:                          
--     ant:                         NO
--     JNI:                         NO
--     Java wrappers:               NO
--     Java tests:                  NO
-- 
============================================================================================


  


  ffmpeg info :

  


  ============================================================================================
ffmpeg
ffmpeg version 4.2.4-1ubuntu1.0firefly5 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.4.0-1ubuntu1~20.04.1)
  configuration: --prefix=/usr --extra-version=1ubuntu1.0firefly5 --toolchain=hardened --libdir=/usr/lib/aarch64-linux-gnu --incdir=/usr/include/aarch64-linux-gnu --arch=arm64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-libdrm --enable-librga --enable-rkmpp --enable-version3 --disable-libopenh264 --disable-vaapi --disable-vdpau --disable-decoder=h264_v4l2m2m --disable-decoder=vp8_v4l2m2m --disable-decoder=mpeg2_v4l2m2m --disable-decoder=mpeg4_v4l2m2m --enable-shared --disable-doc
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Hyper fast Audio and Video encoder
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...
====================================================================================