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• How can I make windows "like" the mp4 files I create in Linux and sync with Rsync

  17 juillet 2019, par Geoff Fox

  I am a meteorologist on TV remotely from a studio I built. My control room uses a TriCaster, an amazing studio-in-a-box which runs on a Windows 7 variant. I make my weather maps myself on a Centos 7 machine — around 40,000/day.

  I don’t entirely understand the problem, but here’s a quote from someone helping me at NewTek (the TriCaster company)

  Rsync is built on a *nix based environment where all the file permissions and attributes are based on the Linux environment. There is no meaning for this in NTFS and Windows. The result is you get files that will most likely have the read-only flag set or no flag at all. Other attributes will be delivered as null. I’m sure from your own programming experience, programs don’t like null values and they generally have to be accounted for very specifically.

  And so the finely tuned TriCaster stumbles, meaning lost frames or other problems caused by my short weather animations.

  Here are some samples of the Rsync code I use

  rsync -r -t -s -v --no-p --chmod=ugo=rwX /var/www/html/output/loops/mp4/conus*.mp4 /mnt/tricaster/Clips/Import
rsync -r -t -s -v --no-p --chmod=ugo=rwX /var/www/html/output/loops/mp4/nebraska*.mp4 /mnt/tricaster/Clips/Import
rsync -r -t -s -v --no-p --chmod=ugo=rwX /var/www/html/output/loops/mp4/northernplains*.mp4 /mnt/tricaster/Clips/Import

  These are mp4 files. They are only used locally. I really don’t care what flags are checked and permissions filled as long as Windows 7 doesn’t care.

  At this point I always like to tell folks, though I do write some code my last computer class was in high school,’67-68 semester. Thanks in advance for your help.

• very low latency streaminig with ffmpeg using a webcam

  22 mars 2017, par userDtrm

  I’m trying to configure ffmpeg to do a real-time video streaming using a webcam. The ffmpeg encoder command I use is as follows.

  ffmpeg -f v4l2 -input_format yuyv422 -s 640x480 -i /dev/video0 -c:v libx264 -profile:v baseline -trellis 0 -subq 1 -level 32 -preset superfast -tune zerolatency -me_method epzs -crf 30 -threads 0 -bufsize 1 -refs 4 -coder 0 -b_strategy 0 -bf 0 -sc_threshold 0 -x264-params vbv-maxrate=2000:slice-max-size=1500:keyint=30:min-keyint=10: -pix_fmt yuv420p -an -f mpegts udp://192.168.1.8:5001

  The ffplay command used to display the video feed is,

  ffplay -analyzeduration 1 -fflags -nobuffer -i udp://192.168.1.8:5001

  However, I’m experiencing a latency of 0.5 - 1.0s latency in the video stream. Is there a way to reduce this to a number less than 100ms. Also, when I replace the v4l2 camera capture with a screen capture using x11grab, the stream is almost real-time and I experience no noticeable delays. Moreover, changing the encoder from x264 to mpeg2 had no effect on the latency. In addition, the statistics from the ffmpeg shows that the encoder is performing at a 30fps rate, which I believe indicates that the encoding is real-time. This leaves me with only one reason for the experienced delay.

  • Is there a significant delay in buffers when using v4l2 during video capturing in a webcam ?
  • I don’t think the transmission delay is in effect in this case as I see no latencies when screen capture is used under the same conditions.
  • Can this latency be further reduced ?. Can someone think of a different encoder configuration to be used instead of the one that I’ve been using ?.

  Any suggestions or assistance is highly appreciated.

  Thank You.

• very low latency streaminig with ffmpeg using a webcam

  22 mars 2017, par userDtrm

  I’m trying to configure ffmpeg to do a real-time video streaming using a webcam. The ffmpeg encoder command I use is as follows.

  ffmpeg -f v4l2 -input_format yuyv422 -s 640x480 -i /dev/video0 -c:v libx264 -profile:v baseline -trellis 0 -subq 1 -level 32 -preset superfast -tune zerolatency -me_method epzs -crf 30 -threads 0 -bufsize 1 -refs 4 -coder 0 -b_strategy 0 -bf 0 -sc_threshold 0 -x264-params vbv-maxrate=2000:slice-max-size=1500:keyint=30:min-keyint=10: -pix_fmt yuv420p -an -f mpegts udp://192.168.1.8:5001

  The ffplay command used to display the video feed is,

  ffplay -analyzeduration 1 -fflags -nobuffer -i udp://192.168.1.8:5001

  However, I’m experiencing a latency of 0.5 - 1.0s latency in the video stream. Is there a way to reduce this to a number less than 100ms. Also, when I replace the v4l2 camera capture with a screen capture using x11grab, the stream is almost real-time and I experience no noticeable delays. Moreover, changing the encoder from x264 to mpeg2 had no effect on the latency. In addition, the statistics from the ffmpeg shows that the encoder is performing at a 30fps rate, which I believe indicates that the encoding is real-time. This leaves me with only one reason for the experienced delay.

  • Is there a significant delay in buffers when using v4l2 during video capturing in a webcam ?
  • I don’t think the transmission delay is in effect in this case as I see no latencies when screen capture is used under the same conditions.
  • Can this latency be further reduced ?. Can someone think of a different encoder configuration to be used instead of the one that I’ve been using ?.

  Any suggestions or assistance is highly appreciated.

  Thank You.