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• Problems piping ffmpeg to flac encoder

  19 mai 2019, par Sebastian Olsen

  I need to encode a flac file with seektables, ffmpeg’s flac encoder does not include seektables, so I need to use the flac CLI. I’m trying to make it possible to convert any arbitrary audio file to a seekable flac file by first piping it through ffmpeg, then to the flac encoder.

  export const transcodeToFlac: AudioTranscoder<{}> = ({
  
    source,
  
    destination
  
  }) => {
  
    return new Promise((resolve, reject) => {
  
      let totalSize = 0
  
  
  
      const { stdout: ffmpegOutput, stderr: ffmpegError } = spawn("ffmpeg", [
  
        "-i",
  
        source,
  
        "-f",
  
        "wav",
  
        "pipe:1"
  
      ])
  
  
  
      const { stdout: flacOutput, stdin: flacInput, stderr: flacError } = spawn(
  
        "flac",
  
        ["-"]
  
      )
  
  
  
      flacOutput.on("data", (buffer: Buffer) => {
  
        totalSize += buffer.byteLength
  
      })
  
  
  
      ffmpegError.on("data", error => {
  
        console.log(error.toString())
  
      })
  
  
  
      flacError.on("data", error => {
  
        console.log(error.toString())
  
      })
  
  
  
      //stream.on("error", reject)
  
  
  
      destination.on("finish", () => {
  
        resolve({
  
          mime: "audio/flac",
  
          size: totalSize,
  
          codec: "flac",
  
          bitdepth: 16,
  
          ext: "flac"
  
        })
  
      })
  
  
  
      ffmpegOutput.pipe(flacInput)
  
      flacOutput.pipe(destination)
  
    })
  
  }

  While this code works, the resulting flac file is not correct. The source audio is of duration 06:14, but the flac file is of duration 06:45:47. Encoding the flac manually without piping ffmpeg to it works fine, but I cannot do that in a server environment where I need to utilize streams.

  Here’s what the flac encoder outputs when transcoding :

  flac 1.3.2
  
  Copyright (C) 2000-2009  Josh Coalson, 2011-2016  Xiph.Org Foundation
  
  flac comes with ABSOLUTELY NO WARRANTY.  This is free software, and you are
  
  welcome to redistribute it under certain conditions.  Type `flac' for details.
  
  
  
  -: WARNING: skipping unknown chunk 'LIST' (use --keep-foreign-metadata to keep)
  
  -: WARNING, cannot write back seekpoints when encoding to stdout
  
  -: 0% complete, ratio=0.357
  
  0% complete, ratio=0.432
  
  0% complete, ratio=0.482
  
  0% complete, ratio=0.527
  
  0% complete, ratio=0.541
  
  1% complete, ratio=0.554
  
  1% complete, ratio=0.563
  
  1% complete, ratio=0.571
  
  size=   36297kB time=00:03:30.70 bitrate=1411.2kbits/s speed= 421x
  
  1% complete, ratio=0.572
  
  1% complete, ratio=0.570
  
  1% complete, ratio=0.577
  
  1% complete, ratio=0.583
  
  1% complete, ratio=0.584
  
  1% complete, ratio=0.590
  
  1% complete, ratio=0.592
  
  size=   64512kB time=00:06:14.49 bitrate=1411.2kbits/s speed= 421x
  
  video:0kB audio:64512kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead:
  
  0.000185%
  
  
  
  -: WARNING: unexpected EOF; expected 1073741823 samples, got 16510976 samples
  
  2% complete, ratio=0.579

• ffmpeg : Cannot find a matching stream for unlabeled input pad 0 on filter Parsed_pad_5

  26 mars 2019, par rsswtmr

  This shouldn’t be that hard. I’m trying to combine three disparate video sources. I’m upscaling them to a consistent 1280x720 frame, with black backgrounds for letterboxing, and trying to concatenate to the output file. The two input files are show segments, and the bumper is a random commercial that goes in the middle.

  On an iMac Pro, System 10.14.3, ffmpeg 4.1.1. The command I’m trying to make work is :

  ffmpeg -y -hide_banner -i "input1.mkv" -i "bumper.mkv" -i "input2.mkv" -filter_complex '[0:v]scale=1280x720:force_original_aspect_ratio=increase[v0],pad=1280x720:max(0\,(ow-iw)/2):max(0\,(oh-ih)/2):black[v0]; [1:v]scale=1280x720:force_original_aspect_ratio=increase[v1],pad=1280x720:max(0\,(ow-iw)/2):max(0\,(oh-ih)/2):black[v1]; [2:v]scale=1280x720:force_original_aspect_ratio=increase[v2],pad=1280x720:max(0\,(ow-iw)/2):max(0\,(oh-ih)/2):black[v2]; [v0][0:a][v1][1:a][v2][2:a]concat=n=3:v=1:a=1 [outv] [outa]' -map "[outv]" -map "[outa]" 'output.mkv'

  The resulting frame I get back is :

  [h264 @ 0x7fbec9000600] [verbose] Reinit context to 720x480, pix_fmt: yuv420p
  
  [info] Input #0, matroska,webm, from 'input1.mkv':
  
  [info]   Metadata:
  
  [info]     encoder         : libebml v0.7.7 + libmatroska v0.8.1
  
  [info]     creation_time   : 2009-07-20T01:33:54.000000Z
  
  [info]   Duration: 00:12:00.89, start: 0.000000, bitrate: 1323 kb/s
  
  [info]     Stream #0:0(eng): Video: h264 (High), 1 reference frame, yuv420p(progressive, left), 708x480 (720x480) [SAR 10:11 DAR 59:44], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
  
  [info]     Stream #0:1(eng): Audio: ac3, 48000 Hz, stereo, fltp, 160 kb/s (default)
  
  [info]     Metadata:
  
  [info]       title           : English AC3
  
  [info]     Stream #0:2(eng): Subtitle: subrip
  
  [h264 @ 0x7fbec9019a00] [verbose] Reinit context to 304x240, pix_fmt: yuv420p
  
  [info] Input #1, matroska,webm, from 'bumper.mkv':
  
  [info]   Metadata:
  
  [info]     CREATION_TIME   : 2019-03-15T15:16:00Z
  
  [info]     ENCODER         : Lavf57.7.2
  
  [info]   Duration: 00:00:18.18, start: 0.000000, bitrate: 274 kb/s
  
  [info]     Stream #1:0: Video: h264 (Main), 1 reference frame, yuv420p(tv, smpte170m/smpte170m/bt709, progressive, left), 302x232 (304x240) [SAR 1:1 DAR 151:116], 29.97 fps, 29.97 tbr, 1k tbn, 180k tbc (default)
  
  [info]     Stream #1:1: Audio: aac (LC), 44100 Hz, stereo, fltp, delay 2111 (default)
  
  [info]     Metadata:
  
  [info]       title           : Stereo
  
  [error] Truncating packet of size 3515 to 1529
  
  [h264 @ 0x7fbec9014600] [verbose] Reinit context to 704x480, pix_fmt: yuv420p
  
  [h264 @ 0x7fbec9014600] [info] concealing 769 DC, 769 AC, 769 MV errors in I frame
  
  [matroska,webm @ 0x7fbec9011e00] [error] Read error at pos. 50829 (0xc68d)
  
  [info] Input #2, matroska,webm, from 'input2.mkv':
  
  [info]   Metadata:
  
  [info]     encoder         : libebml v0.7.7 + libmatroska v0.8.1
  
  [info]     creation_time   : 2009-07-19T22:37:48.000000Z
  
  [info]   Duration: 00:10:07.20, start: 0.000000, bitrate: 1391 kb/s
  
  [info]     Stream #2:0(eng): Video: h264 (High), 1 reference frame, yuv420p(progressive, left), 704x480 [SAR 10:11 DAR 4:3], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
  
  [info]     Stream #2:1(eng): Audio: ac3, 48000 Hz, stereo, fltp, 160 kb/s (default)
  
  [info]     Metadata:
  
  [info]       title           : English AC3
  
  [info]     Stream #2:2(eng): Subtitle: subrip
  
  [Parsed_scale_0 @ 0x7fbec8716540] [verbose] w:1280 h:720 flags:'bilinear' interl:0
  
  [Parsed_scale_2 @ 0x7fbec8702480] [verbose] w:1280 h:720 flags:'bilinear' interl:0
  
  [Parsed_scale_4 @ 0x7fbec8702e40] [verbose] w:1280 h:720 flags:'bilinear' interl:0
  
  [fatal] Cannot find a matching stream for unlabeled input pad 0 on filter Parsed_pad_5
  
  [AVIOContext @ 0x7fbec862bfc0] [verbose] Statistics: 104366 bytes read, 2 seeks
  
  [AVIOContext @ 0x7fbec870a100] [verbose] Statistics: 32768 bytes read, 0 seeks
  
  [AVIOContext @ 0x7fbec87135c0] [verbose] Statistics: 460284 bytes read, 2 seeks

  I have no idea what Parsed_pad_5 means. I Googled Cannot find a matching stream for unlabeled input pad and found absolutely no explanation, anywhere. I’m a relative ffmpeg newbie. Before I start rooting around in the source code, can anyone point me in the right direction ? Thanks in advance.

• Evolution #4300 (Nouveau) : Rendre facultatif les plugins-dist

  1er mars 2019, par Franck D

  Hello :-)
  Le commit de toutati https://zone.spip.net/trac/spip-zone/changeset/114194/spip-zone m’a fait repenser à ce vieux sujet (2009) https://blog.spip.net/SPIP-Core-tout-change-rien-ne-change.html
  Jluc avait fait un sujet à ce propos https://contrib.spip.net/plugins-dist-indispensables-ou-non
  Je me doute que cela représente un boulot de malade... mais ne faudrait’il pas dire au moins dans la F.A.Q. https://www.spip.net/fr_rubrique170.html les plugins-dist qui sont encore obligatoire ?

  J’ai fait le choix de "evolution" et non de "documentation" concernant le ticket, car sans ticket personne n’y pense :-D
  Pour spip 3.3, c’est sans doute un peu tard, mais à chaque sortie majeure, ne serait’il pas possible de rendre au moins "un" plugins-dist optionnel ?

  Pour le moment, en spip 3.3 [24240], il y a comme plugins-dist https://zone.spip.net/trac/spip-zone/browser/spip-zone/_core_/plugins
  Mais tous ne sont pas obligatoirement installer avec la dist (grenier, ?)
  Faudrait rayer les plugs qui sont en options

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