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• Why does ffmpeg hang indefinitely when composing videos ?

  11 octobre 2022, par Brendan Hill

  I am executing ffmpeg commands in a Java microservice (which runs dockerised in kubernetes in a temporary pod created by KEDA from an Amazon SQS queue... but unlikely to be relevant).

  


  About 30% of the time, the ffmpeg process hangs indefinitely :

  


  
/usr/local/bin/ffmpeg 
     -i /tmp/transcode-3b928f5f-3cd9-4cd6-9175-b7c1621aa7ce13592236077853079159/person1.mkv 
     -i /tmp/transcode-3b928f5f-3cd9-4cd6-9175-b7c1621aa7ce13592236077853079159/person2.mkv
     -filter_complex [0:v][1:v]hstack=inputs=2[v];[0:a]aresample=async=1000[0sync];[1:a]aresample=async=1000[1sync];[0sync][1sync]amix[a] 
     -map [v] 
     -map [a] 
     -c:v libx264 
     -crf 18 
     -ac 2 
     -vsync 1 
     -r 25 
     -shortest /tmp/transcode-3b928f5f-3cd9-4cd6-9175-b7c1621aa7ce13592236077853079159/composed.mp4



  


  This causes the Java code to wait indefinitely :

  


  
        Process proc = Runtime.getRuntime().exec(cmd);

        StreamConsumer outConsumer = new StreamConsumer(proc.getInputStream(), stdout);
        StreamConsumer errConsumer = new StreamConsumer(proc.getErrorStream(), stderr);

        // execute data read/write in separate threads
        outExecutor.submit(outConsumer);
        errorExecutor.submit(errConsumer);

        proc.waitFor() // Hangs indefinitely, with ~30% probability



  


  It is not specifically about the video files because they generally work on retry (with similar 30% failure probability so sometimes several retries are necessary). Of course, since it hangs indefinitely instead of exiting with failure, it has to wait hours before we risk another retry.

  


  


  1. Why is ffmpeg hanging indefinitely and how to fix ?

     


  


  2. Can I get ffmpeg to fail early instead of hanging indefinitely (so I can trigger retry immediately) ?

     


  


  3. I see many questions and posts about ffmpeg hanging indefinitely. Is ffmpeg inherently unstable ?

     


  


  


• swscale/aarch64 : add hscale specializations

  26 mai 2022, par Swinney, Jonathan

  swscale/aarch64 : add hscale specializations
  This patch adds code to support specializations of the hscale function
  
  and adds a specialization for filterSize == 4.
  ff_hscale8to15_4_neon is a complete rewrite. Since the main bottleneck
  
  here is loading the data from src, this data is loaded a whole block
  
  ahead and stored back to the stack to be loaded again with ld4. This
  
  arranges the data for most efficient use of the vector instructions and
  
  removes the need for completion adds at the end. The number of
  
  iterations of the C per iteration of the assembly is increased from 4 to
  
  8, but because of the prefetching, there must be a special section
  
  without prefetching when dstW < 16.
  This improves speed on Graviton 2 (Neoverse N1) dramatically in the case
  
  where previously fs=8 would have been required.
  before : hscale_8_to_15__fs_8_dstW_512_neon : 1962.8
  
  after : hscale_8_to_15__fs_4_dstW_512_neon : 1220.9
  Signed-off-by : Jonathan Swinney <jswinney@amazon.com>
  
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libswscale/aarch64/hscale.S
  • [DH] libswscale/aarch64/swscale.c
  • [DH] libswscale/utils.c

• RTMP streaming not working with fluent-ffmpeg and gl

  15 avril 2023, par Smile

  I'm trying to send opengl rendering results to rtmp using gl and fluent-ffmpeg packages.
  
The render function writes opengl output to glBuf.
  
And the render function is called about 60 times per second.
  
And it calls ffmpeg with that glBuf as input.

  


  import ffmpeg from "fluent-ffmpeg";
import GL from "gl";
import { env } from "./env";
import { PassThrough } from "stream";

const WIDTH = 1920;
const HEIGHT = 1080;
const gl = GL(WIDTH, HEIGHT);

const glBuf = new PassThrough();
const render = () => {
  gl.viewport(0, 0, WIDTH, HEIGHT);
  gl.clearColor(0, 0, 0, 1);
  gl.clear(gl.COLOR_BUFFER_BIT);

  const pixels = new Uint8Array(WIDTH * HEIGHT * 4);
  gl.readPixels(0, 0, WIDTH, HEIGHT, gl.RGBA, gl.UNSIGNED_BYTE, pixels);
  glBuf.write(pixels);
};

const FRAMES = 10;
setInterval(() => {
  for (let i = 0; i < FRAMES; i++) {
    render();
  }
}, FRAMES * 1.1 * (1000 / 60));

ffmpeg()
  .input(glBuf)
  .inputFormat("rawvideo")
  .inputOptions([`-video_size ${WIDTH}x${HEIGHT}`, "-pix_fmt rgba"])
  .inputFPS(60)
  .outputFormat("flv")
  .outputOptions([
    "-c:v libx264",
    "-preset veryfast",
    "-maxrate 3000k",
    "-bufsize 6000k",
    "-pix_fmt yuv420p",
    "-g 60",
    "-c:a aac",
    "-b:a 160k",
    "-ac 2",
  ])
  .on("error", (err) => {
    console.error(err);
  })
  .output(`${env.stream_url}/${env.stream_key}`)
  .run();


  


  However, stream health shows No data. That is, the data is ignored.
  
Not works

  


  So I modified the code to save flv file. It works then.

  


  import ffmpeg from "fluent-ffmpeg";
import GL from "gl";
import { env } from "./env";
import { PassThrough } from "stream";

const WIDTH = 1920;
const HEIGHT = 1080;
const gl = GL(WIDTH, HEIGHT);

const glBuf = new PassThrough();
const render = () => {
  gl.viewport(0, 0, WIDTH, HEIGHT);
  gl.clearColor(0, 0, 0, 1);
  gl.clear(gl.COLOR_BUFFER_BIT);

  const pixels = new Uint8Array(WIDTH * HEIGHT * 4);
  gl.readPixels(0, 0, WIDTH, HEIGHT, gl.RGBA, gl.UNSIGNED_BYTE, pixels);
  glBuf.write(pixels);
};

const FRAMES = 10;
const renderInterval = setInterval(() => {
  for (let i = 0; i < FRAMES; i++) {
    render();
  }
}, FRAMES * 1.1 * (1000 / 60));

setTimeout(() => {
  clearInterval(renderInterval);
  glBuf.end();
  console.log("done!");
}, 3000);

ffmpeg()
  .input(glBuf)
  .inputFormat("rawvideo")
  .inputOptions([`-video_size ${WIDTH}x${HEIGHT}`, "-pix_fmt rgba"])
  .inputFPS(60)
  .outputFormat("flv")
  .outputOptions([
    "-c:v libx264",
    "-preset veryfast",
    "-maxrate 3000k",
    "-bufsize 6000k",
    "-pix_fmt yuv420p",
    "-g 60",
    "-c:a aac",
    "-b:a 160k",
    "-ac 2",
  ])
  .on("error", (err) => {
    console.error(err);
  })
  .output(`output.flv`)
  .run();



  


  It works then

  


  Why doesn't first code work ?