[FFmpeg-devel] [PATCH] libx264: fix -b_qfactor and -chromaoffset

[Michael Niedermayer]

On Sat, Aug 23, 2014 at 08:59:41PM +0800, Hii wrote:
> Currently -b_qfactor and -chromaoffset have no effect in libx264,
> the attached patch is an attempt to fix the issue.
> 
> Move the corresponding lines after x264_param_default_preset() to
> prevent them being overwritten by it, make the two parameters
> functional.
> Also make b_qfactor changeable by x264's tunings after the move.
> 
> (feel free to edit the commit message as I am not a native English speaker.)
> 
> 

>  libx264.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> affb26a7840db085fb82ac8e24e5fe5770774113  0001-libx264-fix-b_qfactor-and-chromaoffset.patch
> From d8597d3f708c21deae40b21754173763c5a13658 Mon Sep 17 00:00:00 2001
> From: Hii <hiiragikei at gmail.com>
> Date: Sat, 23 Aug 2014 17:08:02 +0800
> Subject: [PATCH] libx264: fix -b_qfactor and -chromaoffset
> 
> ---
>  libavcodec/libx264.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/libx264.c b/libavcodec/libx264.c
> index 7793581..8aff14d 100644
> --- a/libavcodec/libx264.c
> +++ b/libavcodec/libx264.c
> @@ -371,8 +371,6 @@ static av_cold int X264_init(AVCodecContext *avctx)
>  
>      x4->params.b_deblocking_filter         = avctx->flags & CODEC_FLAG_LOOP_FILTER;
>  
> -    x4->params.rc.f_pb_factor             = avctx->b_quant_factor;
> -    x4->params.analyse.i_chroma_qp_offset = avctx->chromaoffset;
>      if (x4->preset || x4->tune)
>          if (x264_param_default_preset(&x4->params, x4->preset, x4->tune) < 0) {
>              int i;
> @@ -430,6 +428,9 @@ static av_cold int X264_init(AVCodecContext *avctx)
>  
>      if (avctx->i_quant_factor > 0)
>          x4->params.rc.f_ip_factor         = 1 / fabs(avctx->i_quant_factor);
> +    if (avctx->b_quant_factor > 0)
> +        x4->params.rc.f_pb_factor         = avctx->b_quant_factor;

> +    x4->params.analyse.i_chroma_qp_offset = avctx->chromaoffset;

i think this would unconditionally override i_chroma_qp_offset
from x264_param_default_preset()

all others are only overridde when explicitly set by the user

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Frequently ignored answer#1 FFmpeg bugs should be sent to our bugtracker. User
questions about the command line tools should be sent to the ffmpeg-user ML.
And questions about how to use libav* should be sent to the libav-user ML.
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