#11232: M4A metadata did not correct indicate VBR
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Reporter: Xafg | Owner: (none)
Type: defect | Status: new
Priority: minor | Component: avformat
Version: git-master | Resolution:
Keywords: mov | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Changes (by MasterQuestionable):
* cc: MasterQuestionable (added)
* component: undetermined => avformat
* summary: ffmpeg -i sample.mp3 -acodec libfdk_aac -vbr 3 -ac 2 out.m4a =>
M4A metadata did not correct indicate VBR
* priority: important => minor
* version: unspecified => git-master
* keywords: libfdk_aac => mov
Comment:
͏ I guess such may not be considered real bug:
͏ Similar to most PNG encoders wouldn't properly write the exact
prediction (pre-filter) method used for the image, in that innocuous meta.
[1]
͏ Mostly just per format requirement blindly indicated as "Adaptive"
disregard.
͏ See also: https://trac.ffmpeg.org/ticket/11002
[ [1]
͏ The data wouldn't be actually used by the decoder. Though required by
format...
͏ And likely impossible to really indicate the exact prediction used:
͏ As each scanline may actually use different prediction method...
͏ See also: https://www.w3.org/TR/PNG-Filters.html ]
͏ The same situation also occurs for the frame rate meta of various
videos:
͏ The claimed FPS in meta typically somewhat mismatches the actual
frame display.
͏ In particular for VFR (Variable Frame Rate).
--
Ticket URL: <https://trac.ffmpeg.org/ticket/11232#comment:1>
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