On Fri, 13 Feb 2015 13:50:23 +0800
Zhaoxiu Zeng <zhaoxiu.z...@gmail.com> wrote:
> From 3cac16572aee4425377e4bc9e496ab5844200a51 Mon Sep 17 00:00:00 2001
> From: Zeng Zhaoxiu <zhaoxiu.z...@gmail.com>
> Date: Fri, 13 Feb 2015 13:27:26 +0800
> Subject: [PATCH 1/2] avcodec/parser: simplify ff_mpeg4video_split()
>
> Signed-off-by: Zeng Zhaoxiu <zhaoxiu.z...@gmail.com>
> ---
> libavcodec/parser.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/libavcodec/parser.c b/libavcodec/parser.c
> index aa25481..83019e7 100644
> --- a/libavcodec/parser.c
> +++ b/libavcodec/parser.c
> @@ -28,6 +28,7 @@
> #include "libavutil/mem.h"
>
> #include "parser.h"
> +#include "internal.h"
>
> static AVCodecParser *av_first_parser = NULL;
>
> @@ -308,13 +309,14 @@ void ff_parse_close(AVCodecParserContext *s)
>
> int ff_mpeg4video_split(AVCodecContext *avctx, const uint8_t *buf,
> int buf_size)
> {
> - int i;
> uint32_t state = -1;
> + const uint8_t *ptr = buf, *end = buf + buf_size;
>
> - for (i = 0; i < buf_size; i++) {
> - state = state << 8 | buf[i];
> + while (ptr < end) {
> + ptr = avpriv_find_start_code(ptr, end, &state);
> if (state == 0x1B3 || state == 0x1B6)
> - return i - 3;
> + return ptr - 4 - buf;
> }
> +
> return 0;
> }
I don't know, it looks more complicated to me now. Following track of
an integer index is much easier than playing with pointer arithmetics.
Also, why this (apparently) can return a negative integer index just
fine, your pointer calculations can go out of the range [buf,
buf+buf_size], possibly leading to undefined behavior. The code
introduces a function call, without actually reducing the number of
lines.
Well, I know nothing about this code, so you don't need to listen to
me. These are just my impressions.
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
