Transcoding Loses Language Tag of Audio Streams

Bug report and feature request
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TonyB
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Transcoding Loses Language Tag of Audio Streams

Post by TonyB » Wed Mar 25, 2020 9:43 am

Hi.
I've been transcoding a video with two audio streams using version 0.8.60 of MediaCoder.
The original audio streams are in Opus, and the target codec is AAC-LC. Nero is auto-selected as encoder.
The transcoding works, but there are the following unexpected changes:
  • Most importantly, the Language attribute of the transcoded audio streams is no longer present. This is particularly painful since the language is a key differentiator for the user.
  • The frame rate changed, but this appears to be a minor issue.
  • A delay of 9ms to the video stream got introduced, which appears to be also only a minor issue.
Please find below the media infos of the first audio stream (original and after transcoding).
A workaround / fix for the Language tag would be very much appreciated.
And I'd love to understand the changes concerning the frame rate and the delay.

=========== Original Mediainfo of Audio-Stream 1 ===========
Audio #1
ID : 2
Format : Opus
Codec ID : A_OPUS
Duration : 23 min 35 s
Bit rate : 124 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 48.0 kHz
Frame rate : 50.000 FPS (960 SPF)
Compression mode : Lossy
Stream size : 20.9 MiB (6%)
Title : Opus ~128 Kbps
Language : German
Default : No
Forced : No

=========== Mediainfo of Transcoded Audio-Stream 1 ===========
Audio #1
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : A_AAC-2
Duration : 23 min 34 s
Bit rate : 128 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 48.0 kHz
Frame rate : 46.875 FPS (1024 SPF)
Compression mode : Lossy
Delay relative to video : 9 ms
Stream size : 21.6 MiB (7%)
Default : Yes
Forced : No

Cheers,
Tony

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