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• How to fix the "No working C compiler found." problem for compiling x264 in Linux ?

  27 février 2023, par gc xu

  Firstly I have read all other solutions related to this problem, including adding path and reinstall yasm, nasm, gcc...
I git clone the source code from https://code.videolan.org/videolan/x264.git.
Then, I run command ./configure, it shows

  


  ./configure: line 169: conftest.log: Invalid argument
./configure: line 169: conftest.log: Invalid argument
./configure: line 169: conftest.log: Invalid argument
./configure: line 169: conftest.log: Invalid argument
No working C compiler found.


  


  I check the file "config.log". It shows :

  


  checking for -Werror=unknown-warning-option... no
Failed commandline was:
--------------------------------------------------
gcc conftest.c  -Wall -I. -I$(SRCPATH)   -Werror=unknown-warning-option   -o conftest
cc1: error: ‘-Werror=unknown-warning-option’: no option -Wunknown-warning-option
--------------------------------------------------
Failed program was:
--------------------------------------------------
int main (void) {  return 0; }
--------------------------------------------------
checking for -Werror=unknown-attributes... no
Failed commandline was:
--------------------------------------------------
gcc conftest.c  -Wall -I. -I$(SRCPATH)   -Werror=unknown-attributes   -o conftest
cc1: error: ‘-Werror=unknown-warning-option’: no option -Wunknown-warning-option
--------------------------------------------------
Failed program was:
--------------------------------------------------
int main (void) {  return 0; }
--------------------------------------------------
checking for -Werror=attributes... no
Failed commandline was:
--------------------------------------------------
gcc conftest.c  -Wall -I. -I$(SRCPATH)   -Werror=attributes   -o conftest
cc1: error: ‘-Werror=unknown-warning-option’: no option -Wunknown-warning-option
--------------------------------------------------
Failed program was:
--------------------------------------------------
int main (void) {  return 0; }
--------------------------------------------------
checking for -Werror=ignored-attributes... no
Failed commandline was:
--------------------------------------------------
gcc conftest.c  -Wall -I. -I$(SRCPATH)   -Werror=ignored-attributes   -o conftest
cc1: error: ‘-Werror=unknown-warning-option’: no option -Wunknown-warning-option
--------------------------------------------------
Failed program was:
--------------------------------------------------
int main (void) {  return 0; }
--------------------------------------------------
x264 configure script
Command line options: "--enable-shared" "--enable-static"

checking whether gcc works... no
Failed commandline was:
--------------------------------------------------
gcc conftest.c -m64  -Wall -I. -I$(SRCPATH)     -m64  -lm -o conftest
cc1: error: ‘-Werror=unknown-warning-option’: no option -Wunknown-warning-option
--------------------------------------------------
Failed program was:
--------------------------------------------------
int main (void) {  return 0; }
--------------------------------------------------
DIED: No working C compiler found.


  


  Plus I wonder is there something to do with nasm ? Becasuse I install nasm with some C grammer problems :

  


  ./config/config.h:659:16: error: duplicate ‘unsigned’
  659 | #define size_t unsigned int
      |                ^~~~~~~~
./config/config.h:659:25: error: two or more data types in declaration specifiers
  659 | #define size_t unsigned int
      |                         ^~~
In file included from /usr/include/string.h:633,
                 from ./include/compiler.h:89,
                 from asm/nasm.c:38:
./include/compiler.h:241:7: error: expected identifier or ‘(’ before ‘__extension__’
  241 | char *strsep(char **, const char *);
      |       ^~~~~~
./include/compiler.h:241:7: error: expected identifier or ‘(’ before ‘)’ token
  241 | char *strsep(char **, const char *);
      |       ^~~~~~
make[1]: *** [asm/nasm.o] Error 1
make[1]: Leaving directory `/mnt/nfs0/gengcheng/ffmpeg-5.0.2/nasm-2.15.05'
make: *** [all] Error 2


  


  I have read all other solutions related to this problem, including adding path and reinstall yasm, nasm, gcc...
I want to install x264 to configure it in ffmpeg. Thanks for all your answers !

  


• Best logical formula to determine perceptual / "experienced" quality of a video, given resolution / fps and bitrate ?

  20 mars 2023, par JamesK

  I am looking for a formula that can provide me with a relatively decent approximation of a Video's playback quality that can be calculated based off of four metrics : width, height, fps, and bitrate (bits/sec). Alternatively, I can also use FFMPEG or similar tools to calculate a Video's playback quality, if any of those tools provide something like what I am looking for here.

  


  An example of what a Video might look like in my problem is as follows :

  


  interface Video {
  /** The width of the Video (in pixels). */
  width: number
  /** The height of the Video (in pixels). */
  height: number
  /** The frame rate of the Video (frames per second). */
  fps: number
  /** The bitrate of the video, in bits per second (e.g. 5_000_000 = 5Mbit/sec) */
  bitrate: number
}


  


  I came up with the following function to compute the average amount of bits available for any given pixel per second :

  


  const computeVideoQualityScalar = (video: Video): number => {
  // The amount of pixels pushed to the display, per frame.
  const pixelsPerFrame = video.width * video.height
  
  // The amount of pixels pushed to the display, per second.
  const pixelsPerSecond = pixelsPerFrame * video.fps
  
  // The average amount of bits used by each pixel, each second,
  // to convey all data relevant to that pixel (e.g. color data, etc)
  const bitsPerPixelPerSecond = video.bitrate / pixelsPerSecond
  
  return bitsPerPixelPerSecond
}


  


  While my formula does do a good job of providing a more-or-less "standardized" assessment of mathematical quality for any given video, it falls short when I try to use it to compare videos of different resolutions to one another. For example, a 1080p60fps video with a bitrate of 10Mbit/sec has a greater visual fidelity (at least, subjectively speaking, to my eyes) than a 720p30fps video with a bitrate of 9Mbit/sec, but my formula would score the 720p30fps video significantly higher than the 1080p60fps video because the 720p video has more bits available per pixel per second than the 1080p video.

  


  I am struggling to come up with ideas as to how to either come up with a different way to calculate the "subjective video quality" for a given video, or extend upon my existing idea here.

  


• ffmpeg "Error reinitializing filters !" on some webm videos

  9 février 2023, par The Blind Hawk

  I have a dozen of webm videos I need to resize with the following :

  


  ffmpeg -i input.webm -vf “scale=w=360:h=270:force_original_aspect_ratio=2,fps=10,crop=360:270” output.webm


  


  I tried the command and it worked fine for some webm videos, but most of the returned the following error :

  


  [AVFilterGraph @ 0x7fcb3db076c0] No such filter: '“scale'
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument
Error while processing the decoded data for stream #0:0
[libopus @ 0x7fcb3c10a000] 1 frames left in the queue on closing
Conversion failed!


  


  I checked that ffmpeg still worked fine with previously successful files.
  
How can I get ffmpeg to work with the remaining wemb videos ?