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• Spawned ffmpeg process in nodejs Transform stream with flow control doesn't process input stream

  30 septembre 2022, par user1832894

  I have implemented a node.js Transform stream class that spawns ffmpeg and streams out the transformed stream at a controlled realtime rate. Below is my _transform() method.

  


  this.rcvd += chunk.length
console.log('received bytes %d', this.rcvd)
const ready = this.ffmpeg.stdin.write(chunk, encoding, err => err
  ? cb(err)
  : ready
    ? cb
    : this.ffmpeg.stdin.once('drain', cb))


  


  I want to write to ffmpeg's stdin stream till it returns false, at which point I wait for the drain event to write more data.

  


  Concurrently, I have a timer that fires every 40 milliseconds that reads ffmpeg's stdout and pushes it to the Transform stream's output (the readable side). Code not complete, but the folllowing describes it well.

  


  const now = Date.now()
const bytesToTransmit = (now - this.lastTx) * 32

const buf = this.ffmpeg.stdout.read()

if (buf == null) return

if (buf.length <= bytesToTransmit) {
  this.push(buf)
  this.lastTx += buf.length * 32
  return
}

this.push(buf.slice(0, bytesToTransmit))
this.lastTx = now

// todo(handle pending buffer)
this.pending = buf.slice(bytesToTransmit)


  


  The issue I am facing is that the first write (of 65k bytes) returns false, and after that I never receive the drain event. FFMpeg doesn't start processing the data until certain amount of data (256k bytes in my case) has been written, and once I start waiting for the drain event, I never recover control.

  


  I've tried a few ffmpeg options like nobuffer but to no avail. What am I doing wrong ? Any ideas would be super helpful.

  


  Thanks !

  


• dxva2_hevc : properly signal the num_delta_pocs from the SPS RPS

  2 mars 2015, par Hendrik Leppkes

  dxva2_hevc : properly signal the num_delta_pocs from the SPS RPS
  ucNumDeltaPocsOfRefRpsIdx needs to contain the flat value from the SPS RPS,
  
  and not the final computed value from the slice header RPS, as this calculation
  
  is done internally by the driver again.
  Sample-Id : http://trailers.divx.com/hevc/Sintel_4k_27qp_24fps_1aud_9subs.mkvi
  

  • [DH] libavcodec/dxva2_hevc.c
  • [DH] libavcodec/hevc.h
  • [DH] libavcodec/hevc_ps.c

• Can I use a text file's content to create a filtered list for ffmpeg ?

  20 octobre 2022, par Angel Lopez Jr

  I am attempting to make a CMD script that will

  


  

  1. Create a text file that lists file names followed by video codec (using ffprobe)

  


  2. Create a new text from the list so that any file with x265 codec is removed from the list (and formated as
file "*filepath*"

  


  3. Run ffmpeg on the edited list to transcode remaining files to x265.

  


  


  I have a script that does #1

  


  for /R %%f IN (*.mkv,*.avi,*.mp4,*.m2ts,*.mts,*.rm,*.m4v) do echo "%%f" >>Probe.txt & ffprobe -v error -hide_banner -of default=noprint_wrappers=0 -print_format flat  -select_streams v:0 -show_entries stream=codec_name "%%f" >>Probe.txt & echo.  >>Probe.txt


  


  which outputs

  


  


  "filepath"
  
streams.stream.0.codec_name="codec"

  


  "filepath"
  
streams.stream.0.codec_name="codec"

  


  


  and I have a script that will do #3

  


  for /R %%f IN (*.mkv,*.avi,*.mp4,*.m2ts,*.mts,*.rm,*.m4v) do ffmpeg -hide_banner -hwaccel_output_format qsv -i "%%f" -c:v libx265 -c:a ac3 -x265-params crf=25 "%%f.mkv"


  


  I am not sure if #2 is even possible though.

  


  End result of task 2 should be that in probe.txt, any line that has a
streams.stream.0.codec_name value of anything besides hevc will have the line immediately above it written to a new txt file with the word file in front.

  


  final goal is getting all three tasks to run under one batch file (each task running sequentially)

  


  Is there any help on what I am missing to be able to unify these and get #2 to happen