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• lavc/h264dsp : optimise R-V V weight for shorter heights

  1er septembre 2024, par Rémi Denis-Courmont

  lavc/h264dsp : optimise R-V V weight for shorter heights
  The height is a power of two of up to 16 rows. The current code was
  
  optimised for large sample counts.
  T-Head C908 :
  
  h264_weight2_8_c :                                      211.7 ( 1.00x)
  
  h264_weight2_8_rvv_i32 :                   before       184.0 ( 1.15x)
  
  h264_weight2_8_rvv_i32 :                   after         54.2 ( 3.90x)
  
  h264_weight4_8_c :                                      285.7 ( 1.00x)
  
  h264_weight4_8_rvv_i32 :                   before       341.2 ( 0.86x)
  
  h264_weight4_8_rvv_i32 :                   after         82.2 ( 3.47x)
  
  h264_weight8_8_c :                                      498.7 ( 1.00x)
  
  h264_weight8_8_rvv_i32 :                   before       683.7 ( 0.73x)
  
  h264_weight8_8_rvv_i64 :                   after        128.5 ( 3.95x)
  
  h264_weight16_8_c :                                     878.2 ( 1.00x)
  
  h264_weight16_8_rvv_i32 :                  unchanged    239.5 ( 3.67x)
  SpacemiT X60 :
  
  h264_weight2_8_c :                                      207.2 ( 1.00x)
  
  h264_weight2_8_rvv_i32 :                   before       259.6 ( 0.80x)
  
  h264_weight2_8_rvv_i32 :                   after         82.2 ( 2.52x)
  
  h264_weight4_8_c :                                      290.8 ( 1.00x)
  
  h264_weight4_8_rvv_i32 :                   before       509.6 ( 0.57x)
  
  h264_weight4_8_rvv_i32 :                   after         61.5 ( 4.73x)
  
  h264_weight8_8_c :                                      498.8 ( 1.00x)
  
  h264_weight8_8_rvv_i32 :                   before      1019.8 ( 0.49x)
  
  h264_weight8_8_rvv_i64 :                   after         71.8 ( 6.95x)
  
  h264_weight16_8_c :                                     874.0 ( 1.00x)
  
  h264_weight16_8_rvv_i32 :                  unchanged    249.0 ( 3.51x)
  

  • [DH] libavcodec/riscv/h264dsp_init.c
  • [DH] libavcodec/riscv/h264dsp_rvv.S

• How to take snapshot with multiple web cameras at the same time using PHP in Centos ?

  13 novembre 2014, par galengodis

  I’m trying to take still photos / snapshots with multiple web cameras at the same time through php / shell_execute.

  This is what I use so I can the cameras in the background.

  shell_exec('ffmpeg -f video4linux2 -s 1280x960 -i /dev/video0 -q:v 0 -b:v 10000k -vcodec mjpeg -vframes 1 /var/www/html/cam1.jpg -y > /dev/null 2>/dev/null &');
  
  
  
  shell_exec('ffmpeg -f video4linux2 -s 1280x960 -i /dev/video1 -q:v 0 -b:v 10000k -vcodec mjpeg -vframes 1 /var/www/html/cam2.jpg -y > /dev/null 2>/dev/null &');

  It outputs only one image from the cameras. If i run them one at a time with the same code everything works. Fyi the "&" at the end makes the php run in background. Read more here about shell_exec background process : Is there a way to use shell_exec without waiting for the command to complete ?

  > [root@localhost ~]# lsusb 
  
  > Bus 001 Device 002: ID 8087:8000 Intel Corp.
  
  > Bus 002 Device 004: ID 1a40:0201 Terminus Technology Inc. FE 2.1
  
  > 7-port Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root
  
  > hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus
  
  > 003 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 002
  
  > Device 006: ID 046d:0825 Logitech, Inc. Webcam C270 Bus 002 Device
  
  > 005: ID 0c45:6340 Microdia
  
  > 
  
  > [root@localhost ~]# find /dev/bus/ /dev/bus/ /dev/bus/usb
  
  > /dev/bus/usb/003 /dev/bus/usb/003/001 /dev/bus/usb/002
  
  > /dev/bus/usb/002/006 /dev/bus/usb/002/005 /dev/bus/usb/002/004
  
  > /dev/bus/usb/002/001 /dev/bus/usb/001 /dev/bus/usb/001/002
  
  > /dev/bus/usb/001/001

  I’ve tried with altering applications between ffmpeg and streamer. So the problem seems to be USB-related. The both cameras are plugged into a USB-hub (with an external power supply). The cameras are of different brands.

  I’m on Centos 7, 64bit.

• is this ffmpeg command optimized ?

  22 juin 2017, par Bob Ramsey

  I have a requirement to take a video, add some plain text, and then add some rotated text at different times, locations, and durations. I want to use processor power in the most efficient way this will run 20,000 times (yes, really, we’re personalizing a video for students at a U.)This is what I finally came up with :

  ffmpeg -y -i INPUT.mp4 -filter_complex 
  
    "drawtext=enable='between(t,14,16)':fontfile=tahoma.ttf:fontsize=54:fontcolor=green:x=10:y=text_h + 10:text='Dana Scully',
  
     drawtext=enable='between(t,19,23)':fontfile=tahoma.ttf:fontsize=16:fontcolor=red:x=150:y=220:text='Dana Scully  \<dana.scully\@fbi.gov\>',
  
     drawtext=enable='between(t,99,104)':fontfile=tahoma.ttf:fontsize=28:fontcolor=green:x=480:y=text_h + 160:text='Dana Scully',
  
     drawtext=enable='between(t,14,16)':fontfile=tahoma.ttf:fontsize=16:fontcolor=yellow:x=40:y=25:text='Dana Scully  \<dana.scully\@fbi.gov\>',
  
     drawtext=enable='between(t,180,186)':fontfile=tahoma.ttf:fontsize=88:fontcolor=green:x=20:y=430:text='Dana Scully'[text];
  
     color=c=#111111:s=1280x720:d=1,format=yuv444p[colorbk];
  
     [colorbk]drawtext=fontfile=tahoma.ttf:fontsize=16:fontcolor=purple:x=(w-text_w)/2:y=(h-text_h)/2:text='by',drawtext=fontfile=tahoma.ttf:fontsize=32:fontcolor=green:x=(w-text_w)/2:y=((h-text_h)/2)+50:text='Dana Scully',rotate=(-.5):ow=1280:oh=720:c=#111111,chromakey=#111111:similarity=0.01,format=yuva444p,colorkey=#111111:0.1[rotated];
  
     [text][rotated]overlay=eval=frame:x='if(gte(t,134),(if(lte(t,137),20,NAN)), NAN)':y=100[out];[out]scale=iw*.25:-1" 
  
     -crf 20 test.mp4

  Is that about as optimized as it is going to get ? I thought ffmpeg would already handle the threads based on the computer’s processor, so no real need to mess with it. The processing will all be done on AWS VMs.

  Rotating the text is what really slows it down.

  Any ideas ?