[FFmpeg-devel] [PATCH 2/3] avformat/avienc: add reserve_index_space option

[Tobias Rapp]

On 25.01.2017 22:49, Michael Niedermayer wrote:
> On Mon, Jan 23, 2017 at 11:12:13AM +0100, Tobias Rapp wrote:
> [...]
>>  libavformat/avi.h                       |    1
>>  libavformat/avienc.c                    |   77 +++++++++++++++++++++++++++++---
>>  libavformat/version.h                   |    2
>>  tests/ref/fate/mpeg4-bsf-unpack-bframes |    2
>>  tests/ref/lavf-fate/avi_cram            |    2
>>  5 files changed, 74 insertions(+), 10 deletions(-)
>> 8dfa5b4ff26ee67c6772bb257a772672bb91aa34  0002-avformat-avienc-add-reserve_index_space-option.patch
>> From 4cc70ffdeb7eeb60e7bbb725bd5885dcacf968d2 Mon Sep 17 00:00:00 2001
>> From: Tobias Rapp <t.rapp at noa-archive.com>
>> Date: Wed, 4 Jan 2017 15:31:29 +0100
>> Subject: [PATCH 2/3] avformat/avienc: add reserve_index_space option
>>
>> Allows the user to reserve space for the ODML master index. A sufficient
>> sized master index in the AVI header avoids storing follow-up master
>> indexes within the 'movi' data later.
>>
>> If the option is omitted or zero the index size is estimated from output
>> duration and bitrate. A worst-case bitrate for video streams is assumed
>> in case it is not available.
>>
>
>> Note: fate reference files changed because the video stream had zero
>> bitrate before and is guessed now.
>
> I dont think this is good
> if the user app says bitrate is 0 the muxer should not replace that by
> the bitrate for a rawvideo stream (when its not rawvideo)
>
> This could be ok for the reserved space calculation but for the file
> bitrate, especially with lossy compressed streams this will likely
> give values that are less correct than before

My assumption was that bitrate=0 corresponds to "unknown" and that a 
large value for MaxBytesPerSec would do less harm than a small/zero value.

Find attached an updated version of the patch with "worst-case bitrate 
guessing" removed.

Regards,
Tobias
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