I'm having trouble transcoding audio in Superstreamer

[insanity54]

I'm seeing a consistent failure of the audio transcoding task in Superstreamer.

Here is how I'm creating a pipeline.

import * as wmill from "windmill-client"

type Stream =
  | {
    type: "video";
    codec: string;
    height: number;
    bitrate: number;
  }
  | {
    type: "audio";
    language: string;
    codec: string;
    bitrate: number;
  };

export function generateVideoStreams(sourceHeight: number) {
  const videoProfiles = [
    { height: 1080, bitrate: 500000 },
    { height: 720, bitrate: 300000 },
    { height: 360, bitrate: 100000 },
    { height: 160, bitrate: 10000 }
  ];

  return videoProfiles
    .filter(profile => profile.height <= sourceHeight)
    .map(profile => ({
      type: "video",
      codec: "h264",
      height: profile.height,
      bitrate: profile.bitrate
    }));
}

export function generateAudioStreams(): Stream[] {
  return [
    {
      type: "audio",
      codec: "aac",
      language: "en",
      bitrate: 300000
    }
  ];
}

function normalizeVideoUrl(video_url: string): string {
  // Return as-is if it starts with http or https
  if (/^https?:\/\//.test(video_url)) {
    return video_url;
  }

  // Remove leading slash if present
  const normalizedPath = video_url.replace(/^\/+/, '');

  // Prepend S3 scheme
  return `s3://${normalizedPath}`;
}


export async function main(video_url: string, video_height: number) {

  let SUPERSTREAMER_API_URL = (await wmill.getVariable('f/fp/SUPERSTREAMER_API_URL'))
  let SUPERSTREAMER_API_TOKEN = (await wmill.getVariable('f/fp/SUPERSTREAMER_API_TOKEN'))

  video_url = normalizeVideoUrl(video_url)

  const streams = generateVideoStreams(video_height).concat(generateAudioStreams());
  let res = await fetch(`${SUPERSTREAMER_API_URL}/jobs/pipeline`, {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${SUPERSTREAMER_API_TOKEN}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      inputs: [
        {
          type: "video",
          path: video_url,
          height: video_height
        },
        {
          type: "audio",
          path: video_url,
          language: "en"
        }
      ],
      streams,
      group: "fp",
      language: "english",
      concurrency: 1,
      public: false,
    })
  })

  let data = await res.json()


  return { body: data, done: true }
}

Pipeline shows an error

child bull:transcode:transcode_2a6ee0fe-5f5f-484f-a0b1-fefe601eff64 failed

Logs

No logs available

Transcode shows an error

child bull:ffmpeg:ffmpeg_0f28bc99-8731-4bf7-a450-23d68aca8745 failed

Logs

    1
    Matched video: {"type":"video","codec":"h264","height":1080,"bitrate":500000,"framerate":29.999226334873214} / {"type":"video","path":"s3://usc/d2ca805d-94d6-4945-98f7-0020ab73351e-concatenated.mp4","height":1080,"framerate":29.999226334873214}

2
Matched video: {"type":"video","codec":"h264","height":720,"bitrate":300000,"framerate":29.999226334873214} / {"type":"video","path":"s3://usc/d2ca805d-94d6-4945-98f7-0020ab73351e-concatenated.mp4","height":1080,"framerate":29.999226334873214}
3
Matched video: {"type":"video","codec":"h264","height":360,"bitrate":100000,"framerate":29.999226334873214} / {"type":"video","path":"s3://usc/d2ca805d-94d6-4945-98f7-0020ab73351e-concatenated.mp4","height":1080,"framerate":29.999226334873214}
4
Matched video: {"type":"video","codec":"h264","height":160,"bitrate":10000,"framerate":29.999226334873214} / {"type":"video","path":"s3://usc/d2ca805d-94d6-4945-98f7-0020ab73351e-concatenated.mp4","height":1080,"framerate":29.999226334873214}
5
Matched audio: {"type":"audio","codec":"aac","bitrate":300000,"language":"en","channels":2} / {"type":"audio","path":"s3://usc/d2ca805d-94d6-4945-98f7-0020ab73351e-concatenated.mp4","language":"en","channels":2}

ffmpeg(audio,en) shows an error

ffmpeg exited with code 1: 

Logs

    1
    Transcode to audio_en_300000_aac.m4a

2
ffmpeg -i https://fp-usc.s3.us-west-000.backblazeb2.com/usc/d2ca805d-94d6-4945-98f7-0020ab73351e-concatenated.mp4?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=000d37f13a933b80000000038%2F20250514%2Fus-west-000%2Fs3%2Faws4_request&X-Amz-Date=20250514T092350Z&X-Amz-Expires=86400&X-Amz-Signature=ed197e2fcecf97bdafab5ecc5f798fbeb33e71f4a11da61462af1f2aad44dbba&X-Amz-SignedHeaders=host&x-id=GetObject -y -f mp4 -vn -ac 2 -c:a aac -b:a 300000 -frag_duration 2240000 -metadata language=en -strict experimental /tmp/superstreamer-15113922-302b-43ee-9da9-46acae9aecc5OPmrTg/audio_en_300000_aac.m4a

So it looks like there is something going wrong with the ffmpeg command, but I'm not sure what.

[insanity54]

Oh I think I found the problem. The test video I'm using has no audio track

[matvp91]

Ooh that explains! Thank you for debugging.