Beet convert spitting out lots of error reading

[CommunicationAnimale]

Problem

When running beet convert, beet prints twice the same error message error reading ... (see below) after every conversion. However every file seems to have been correctly written to its destination, so I'm not sure what the error really is, maybe the error message could be changed to something more informative?

❯ beet convert Disclosure Intro
Disclosure - Settle - Intro
Convert? (Y/n) y
convert: Encoding /home/com/Music/Library/Disclosure/Settle/01 Intro.flac
convert: Finished encoding /home/com/Music/Library/Disclosure/Settle/01 Intro.flac
error reading /home/com/Music/Library/Disclosure/Settle/01 Intro.flac: b'/home/com/Music/Converted/Disclosure/Settle/01 Intro.mkv'
error reading /home/com/Music/Library/Disclosure/Settle/01 Intro.flac: b'/home/com/Music/Converted/Disclosure/Settle/01 Intro.mkv'

Setup

• OS: Fedora 25
• Python version: Python 3.5.3
• beets version: 1.4.4
• Turning off plugins made problem go away (yes/no): N.a

My configuration (output of beet config) is:

lyrics:
    bing_lang_from: []
    fallback:
    bing_lang_to:
    bing_client_secret: REDACTED
    google_engine_ID: REDACTED
    auto: yes
    sources: [google, lyricwiki, musixmatch]
    force: no
    genius_api_key: REDACTED
    google_API_key: REDACTED
directory: ~/Music/Library
convert:
    dest: ~/Music/Converted
    never_convert_lossy_files: yes
    command: ffmpeg -i $source -vn -c:a libopus -vbr on -b:a 128k -threads 0 $dest
    extension: mkv
    formats:
        ogg: ffmpeg -i $source -y -vn -acodec libvorbis -aq 3 $dest
        aac:
            extension: m4a
            command: ffmpeg -i $source -y -vn -acodec aac -aq 1 $dest
        opus: ffmpeg -i $source -y -vn -acodec libopus -ab 96k $dest
        alac:
            extension: m4a
            command: ffmpeg -i $source -y -vn -acodec alac $dest
        flac: ffmpeg -i $source -y -vn -acodec flac $dest
        wma: ffmpeg -i $source -y -vn -acodec wmav2 -vn $dest
        mp3: ffmpeg -i $source -y -vn -aq 2 $dest

    paths: {}
    auto: no
    format: mp3
    copy_album_art: no
    quiet: no
    max_bitrate: 500
    album_art_maxwidth: 0
    pretend: no
    threads: 4
    tmpdir:
    embed: yes

import:
    copy: yes
    move: no
library: ~/.local/share/beets/musiclibrary.db

plugins: [fetchart, lyrics, convert]
fetchart:
    cover_names:
    - cover
    - front
    - art
    - album
    - folder
    google_key: REDACTED
    cautious: no
    maxwidth: 0
    auto: yes
    minwidth: 0
    sources:
    - filesystem
    - coverart
    - itunes
    - amazon
    - albumart
    store_source: no
    google_engine: 001442825323518660753:hrh5ch1gjzm
    enforce_ratio: no
    fanarttv_key: REDACTED

[sampsyo]

Hi! Can you please include a verbose log? You can run beet -vv convert Disclosure Intro.

[CommunicationAnimale]

Sure, here it is:

❯ beet -vv convert Disclosure Intro -d Test
user configuration: /home/com/.config/beets/config.yaml
data directory: /home/com/.config/beets
plugin paths:
Sending event: pluginload
lyrics: Disabling google source: no API key configured.
library database: /home/com/.local/share/beets/musiclibrary.db
library directory: /home/com/Music/Library
Sending event: library_opened
Disclosure - Settle - Intro
Convert? (Y/n) y
convert: Encoding /home/com/Music/Library/Disclosure/Settle/01 Intro.flac
convert: Finished encoding /home/com/Music/Library/Disclosure/Settle/01 Intro.flac
Sending event: write
error reading /home/com/Music/Library/Disclosure/Settle/01 Intro.flac: b'/home/com/Music/Test/Disclosure/Settle/01 Intro.mkv'
convert: embedding album art from /home/com/Music/Library/Disclosure/Settle/cover.jpg
convert: embedding /home/com/Music/Library/Disclosure/Settle/cover.jpg
Sending event: write
error reading /home/com/Music/Library/Disclosure/Settle/01 Intro.flac: b'/home/com/Music/Test/Disclosure/Settle/01 Intro.mkv'
Sending event: after_convert
Sending event: cli_exit

[sampsyo]

OK; thanks! That helps. It looks like the problem is that you're converting to a format that beets itself doesn't support (MKV). The convert plugin tries to set the metadata tags on those converted files after transcoding and can't. We should definitely clarify that error message.

[sampsyo]

OK, I've pushed some changes that should make it clearer what's going on.

On a minor note, I looked into why the error was being printed twice. It looks like the convert plugin writes the file once with the basic tags and then a second time with the album art. This might be worth trying to collapse down into one write call to improve efficiency and reduce confusion.

[CommunicationAnimale]

Thanks! For reference, I simply changed extension: mkv to extension: ogg and everything works great! (Android cannot read opus in .opus files, but apparently accepts both .mkv and .ogg, though only .mkv is documented.)

[sampsyo]

Oh cool! That makes sense. Maybe it's a documentation bug? It does seem odd that they'd only want to support .mkv files, which are usually used for video...

[CommunicationAnimale]

Well, I also tried the other container formats supporting Opus listed on Wikipedia (.opus, .mkv, .webm, .ts .mp4), and only ogg (though it wasn't even mentionned on the Wikipedia page) was displayed by the default music player.
However, if I understood correctly, a .opus file simply is an ogg-encapsulated opus stream with a different extension, so it really is weird that Android accepts .ogg but not .opus...

Edit: I'm using LineageOS, so this behavior might be different on AOSP.