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• Saving highest quality video from video-capture card

  23 décembre 2013, par DusteD

  I have a machine with 2x3 3ghz dual-core xeon and 4x10krpm scsi 320 disks in raid0.
  The capture card is an osprey 560 64 bit pci card.
  Operating system is currently Windows Server 2003.

  The video-stream that I can open with VLC using direct show is rather nice quality.
  However, trying to save this video-stream without loss of quality has proven quite difficult,
  using the h264 codec I am able to achieve a satisfying quality, however, all 4 cores jump to 100% load after a few second and then it start dropping frames, the machine is not powerful enough for realtime encoding. I've not been able to achieve satisfying mpeg1 or 4 quality, no matter which bitrate I set..

  Thing is, the disks in this machine are pretty fast even by todays standard, and they are bored.. I don't care about disk-usage, I want quality.
  I have searched in vain for a way to pump that beautiful videostream that I see in VLC onto the disk for later encoding, I reckon the disks would be fast enough, or maybe something which would apply a light compression, enough that the disks can keep up, but not so much as to loose visible quality.

  I have tried FFMPEG as it seems capable of streaming a yuv4 stream down to the disk, but ofcause FFMPEG is unable to open the dshow device ( same error as this guy Ffmpeg streaming from capturing device Osprey 450e fails )

  Please recommend a capable and (preferably) software which can do this.

• ffmpeg is not capturing udp output

  30 octobre 2020, par Dzidas

  I'm trying to capture UDP output with ffmpeg, but the stream looks empty. Just for background, the output is produced by GoPro camera and I'm connecting to its Wifi. I can see with wireshark a lot of udp packets sent to my ip from GoPro IP, but nothing appears in ffmpeg.

  


  ffplay -fflags nobuffer -f:v mpegts -probesize 8192 udp://10.5.5.9:8554
ffplay version 4.3.1 Copyright (c) 2003-2020 the FFmpeg developers
built with Apple clang version 11.0.0 (clang-1100.0.33.17)
configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1_2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
libavutil      56. 51.100 / 56. 51.100
libavcodec     58. 91.100 / 58. 91.100
libavformat    58. 45.100 / 58. 45.100
libavdevice    58. 10.100 / 58. 10.100
libavfilter     7. 85.100 /  7. 85.100
libavresample   4.  0.  0 /  4.  0.  0
libswscale      5.  7.100 /  5.  7.100
libswresample   3.  7.100 /  3.  7.100
libpostproc    55.  7.100 / 55.  7.100
nan    :  0.000 fd=   0 aq=    0KB vq=    0KB sq=    0B f=0/0


  


  Any idea or suggestion how could I debug or understand the cause ?

  


  Thanks !

  


• Why does ffmpeg remove SEI messages when converting FLV to h264 ?

  22 juin 2020, par Tunji_D

  I have an FLV file with h264 video tags. Each video tag that contains an h264 IDR NAL unit also also contains display orientation SEI, ie my NAL access unit for IDR key frames is [SEI, IDR].

  


  For some reason, converting this FLV file to h264 without the stream copy option strips away all the SEI messages from all IDR frames. In its place, right after the SPS and PPS NAL units, there's a single user unregistered data SEI.

  


  i.e using

  


  ffmpeg -i in.flv out.264


  


  gives [SPS, PPS, SEI, IDR, ...] where the SEI is :

  


  


  x264 - core 155 r2917 0a84d98 - H.264/MPEG-4 AVC codec - Copyleft
2003-2018 - http://www.videolan.org/x264.html - options : cabac=1 ref=3
deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00
mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0
deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=11
lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0
bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1
b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250
keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf
mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40
aq=1:1.00

  


  


  However

  


  ffmpeg -i in.flv -c:v copy out.264


  


  preserves my SEI messages, and pretty much decodes to the raw h264 I put into the FLV muxer to generate the FLV file in the first place. Why does this happen ? Is there a flag to perform encoding but preserve SEI messages ?