During the PoC on Transcoder API, I tried to transcode a source MKV file to HLS output with video, audio and subtitle, but constantly got error of internal error. And the output is never generated.
Job Name: projects/PROJECT-NUMBER/locations/asia-east1/jobs/JOB-ID
The main purpose is to transcode the source video file with multiple audio tracks and subtitles into the output video file with just one select audio track and one select subtitle.
I've checked the logs (link screenshot) and it looks like the customer is trying to extract the text from a video files, which is not supported AFAIK - only standalone scc, srt, and vtt files are supported https://cloud.google.com/transcoder/docs/concepts/overview#supported_inputs_outputs
ranscoder API only supports standalone subtitle files, feel free to submit a feature request for embedded subtitles and our PM will take a look go/gcp-transcoder:site#need-help
The only workaround I can suggest is to extract the subtitle from the original file with ffmpeg or similar program into scc, srt, or vtt format and feed it as a text input to Transcoder API.
AFAIK only the following combinations are supported:
Could you please try either changing the container to fmp4 or caption type to CEA-608/708?
FYI we can't reproduce any of the issues without having access to the input media files.
https://cloud.google.com/transcoder/docs/concepts/stream-mappings#default_text_mapping explains how default text mapping work. This is important to understand for your use case because the order of inputs in the config matters when multiple inputs have text stream in it.