Metadata decoder function runs twice

[vitoyucepi]

Describe the bug The external metadata decoder is called twice. For example, autocue analyzes each file twice.

[lang:3] test called
[lang:3] /tmp/test/music/2.mp3 []
[lang:3] test called
[lang:3] /tmp/test/music/2.mp3 [("encoder", "Lavf60.16.100"), ("title", "music_2")]

To Reproduce

1. ffmpeg -f lavfi -i "sine=frequency=100:duration=3" -c:a libmp3lame -b:a 128k -metadata title=music_1 -y 1.mp3

2. main.liq

   music_dir = "/tmp/test/"
   
   def test(~metadata, filename)
    log("test called")
    log("#{filename} #{metadata}")
    []
   end
   decoder.metadata.add("test", test)
   
   radio = playlist("/tmp/test/")
   
   output.dummy(radio, fallible=true)

3. services:
    liquidsoap:
      image: savonet/liquidsoap:v2.2.5
      command:
        - /tmp/test/main.liq
      volumes:
        - ./:/tmp/test

Expected behavior The Metadata decoder function should be called only once.

Version details

• OS: alpine in docker
• Version: 2.2.5, 530afaf0

Install method source

Common issues

3887, #3874.

https://github.com/savonet/liquidsoap/discussions/3957#discussioncomment-9729079

[Moonbase59]

I wonder if that happens because enable_autocue_metadata() just reads file tags, and when an annotated request hits in, we want the annotated values as well? Just guessing, of course.

We’ve been having problems there, and in AzuraCast we’re now just using the protocol, not enable… anymore.

In

def cue_file(~request_metadata, ~file_metadata, filename) =

I actually get two kinds of metadata, and must consolidate them:

  # combine request & file metadata into one list, where
  # request_metadata (annotations) takes precedence
  metadata = list.fold(
    fun(res, entry) ->
      if list.assoc.mem(fst(entry), res) then
        res
      else
        [...res, entry]
      end,
      request_metadata,
      file_metadata
  )

[vitoyucepi]

I used git bisect to find the commit after which the behavior manifested itself. In the 2.2.x branch, it was c11cc5ef3e60fbd8877c2455d03678261b25a50b. In the main branch it was 939eba26a13b35a4edae2db13b6a22cd6bbccac8, but the output is slightly different, but test is called twice.