atranscoder-rpc/README.md

atranscoder-rpc

Audio transcoder with simple HTTP API. Work in progress.

How to Use

Transcoding can be done like this:

1. Use neur0toxine/atranscoder-rpc Docker image.
2. Upload file for transcoding:

curl --location 'http://localhost:8090/enqueue' \
--form 'file=@"/home/user/Music/test.mp3"' \
--form 'format="mp4"' \
--form 'codec="libfdk_aac"' \
--form 'codec_opts="profile=aac_he"' \
--form 'bit_rate="64000"' \
--form 'max_bit_rate="64000"' \
--form 'sample_rate="44100"' \
--form 'channel_layout="stereo"' \
--form 'callback_url="http://127.0.0.1:8909/callback"'

3. Your callback_url will receive JSON response with job ID and error in case of failure. Error will be null if transcoding was successful.
4. You can download transcoded file like this (replace job_id with the ID you've received):

curl -L http://localhost:8090/get/job_id -o file.mp4

You can also enqueue a remote file like this:

curl --location 'http://localhost:8090/enqueue_url' \
--header 'Content-Type: application/json' \
--data '{
    "format": "mp4",
    "codec": "libfdk_aac",
    "codec_opts": "profile=aac_he",
    "bit_rate": 64000,
    "max_bit_rate": 64000,
    "sample_rate": 44100,
    "channel_layout": "stereo",
    "url": "https://upload.wikimedia.org/wikipedia/commons/c/c8/Example.ogg",
    "callback_url": "http://127.0.0.1:8909/callback"
}'

Mandatory fields:

• format
• codec
• sample_rate
• url (for /enqueue_url)

Configuration

You can change configuration using these environment variables:

• LISTEN - change this environment variable to change TCP listen address. Default is 0.0.0.0:8090.
• NUM_WORKERS - can be used to change how many threads will be used to transcode incoming files. Default is equal to logical CPUs.
• TEMP_DIR - this can be used to change which directory should be used to store incoming downloads and transcoding results. Useful if you want to use a Docker volume for this. Default is system temp directory (/tmp for Linux).
• LOG_LEVEL - changes log verbosity, default is info.
• MAX_BODY_SIZE - changes max body size for /enqueue. Default is 100MB, maximum is 1GiB (which is still a lot for the multipart form).
• RESULT_TTL_SEC - sets result ttl in seconds, minimum 60 seconds. Default is 3600 (transcoding results are being kept and can be downloaded for an hour).
• FFMPEG_VERBOSE - if set to 1 changes FFmpeg log level from quiet to trace.

Roadmap

• Implement somewhat acceptable error handling.
• Remove old conversion results and input files that are older than 1 hour.
• Remove input file after transcoding it.
• Do not upload files directly, add download route with streaming instead.
• Conversion from OGG Opus mono to HE-AAC v1 Stereo outputs high-pitched crackling audio.
• Conversion from OGG Opus mono to AAC sometimes crashes the app with SIGSEGV (this can be seen more often with very short audio).
• If FFmpeg fails, send_error won't be called - fix that. It actually works, I just didn't notice before.
• Ability to enqueue a remote file.
• Default errors are returned in plain text. Change it to the JSON.
• Docker image for amd64 and arm64 (currently only amd64 is supported because arm64 cross-compilation with QEMU is sloooooooooooowwwww...).
• Tests!