easy-ott-subtitles

OTT (DASH/HLS) automatic subtitles translator/transcriber. Suitable to VoD and Live OTT streams.

It is basically a manifest manipulator for HLS and DASH. It adds subtitle(s) track(s) to the origin manifest according to the URL parameters (see instructions below). It allows very easy intergation: no changes to the origin stream are needed, work is done on-the-fly. Original Video/Audio/Text tracks are directed to the origin server. Only added text tracks are served from easy-ott-subtitles server.

Currently using Google Cloud Translation and Speech-to-Text APIs.

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Installation

• Create virtual enviroment

$ virtualenv -p python3 venv
$ source venv/bin/activate

• Install python dependencies

$ pip install -r requirements.txt

• Install FFmpeg (used for transcribe only)

$ sudo apt-get install ffmpeg

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Configuration

• Configure Google Cloud service account key

1. Generate service account key json file.
2. Copy the file to folder 'google_key'
3. Configure project id and service account key file path in ini file under GOOGLE_API:

[GOOGLE_API]
PROJECT_ID = <project_id>
SERVICE_ACCOUNT_FILE = google_key/<service_account_key_file_path>

• Default port number is 8500. This can be changed in ini file under HTTP_SERVER:

[HTTP_SERVER]
EOS_HTTP_PORT_NUMBER = 8500

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Usage

• Start the server

$ python easy-ott-subtitles -c eos.ini

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URL Generation

• To consturct a playout URL, use this formula:

http://<server_ip_address>:<server_port_number>/eos/v1/<dash/hls>/<vod/live>/<translate/transcribe>/<source_language>/<origin_stream_url_base64>/eos_manifest.<m3u8/mpd>?languages=<destination_languages>&default=<default_language>

Example

Transcribe

• Use a sample HLS test stream in English: http://amssamples.streaming.mediaservices.windows.net/91492735-c523-432b-ba01-faba6c2206a2/AzureMediaServicesPromo.ism/manifest(format=m3u8-aapl)

• This stream does not contain any subtitles which we can translate, so we nee to transcribe it.

• Encoded stream URL to Base64: aHR0cDovL2Ftc3NhbXBsZXMuc3RyZWFtaW5nLm1lZGlhc2VydmljZXMud2luZG93cy5uZXQvOTE0OTI3MzUtYzUyMy00MzJiLWJhMDEtZmFiYTZjMjIwNmEyL0F6dXJlTWVkaWFTZXJ2aWNlc1Byb21vLmlzbS9tYW5pZmVzdChmb3JtYXQ9bTN1OC1hYXBsKQ==

• Construct playout URL with English and German subtitles: http://127.0.0.1:8500/eos/v1/hls/vod/transcribe/en-US/aHR0cDovL2Ftc3NhbXBsZXMuc3RyZWFtaW5nLm1lZGlhc2VydmljZXMud2luZG93cy5uZXQvOTE0OTI3MzUtYzUyMy00MzJiLWJhMDEtZmFiYTZjMjIwNmEyL0F6dXJlTWVkaWFTZXJ2aWNlc1Byb21vLmlzbS9tYW5pZmVzdChmb3JtYXQ9bTN1OC1hYXBsKQ==/eos_manifest.m3u8?languages=en-US,de-DE&default=en-US

• You need to wait a bit (~30 seconds) before start playing, to let the transcribe service to get ahead with the Speech-to-Text process.

Translate

• Use a sample HLS test stream with English subtitles: http://sample.vodobox.com/planete_interdite/planete_interdite_alternate.m3u8

• Encoded stream URL to Base64: aHR0cDovL3NhbXBsZS52b2RvYm94LmNvbS9wbGFuZXRlX2ludGVyZGl0ZS9wbGFuZXRlX2ludGVyZGl0ZV9hbHRlcm5hdGUubTN1OA==

• Construct playout URL with German Subtitles: http://127.0.0.1:8500/eos/v1/hls/vod/translate/en-US/aHR0cDovL3NhbXBsZS52b2RvYm94LmNvbS9wbGFuZXRlX2ludGVyZGl0ZS9wbGFuZXRlX2ludGVyZGl0ZV9hbHRlcm5hdGUubTN1OA==/eos_manifest.m3u8?languages=de-DE&default=de-DE

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HTTPS Server and Caching

This package is using python HTTP server. To make it suitable for production and enable HTTPS + caching for subtitle fragments, you can use Nginx with reverese proxy as the outbound HTTPS server, and enable content caching.