[FFmpeg-devel] [PATCH v2 1/7] Add meaningful error codes and constants.
Vitaliy E Sugrobov
vsugrob at hotmail.com
Fri Nov 30 09:58:52 CET 2012
Replace literals with named constants in several pieces of code
like 'return -1' and 'case 0xab'.
Change the way decoder handles absence of image data in a file:
notify gif_decode_frame() caller with got_picture set to zero
instead of returning -1.
Signed-off-by: Vitaliy E Sugrobov <vsugrob at hotmail.com>
---
libavcodec/gifdec.c | 40 ++++++++++++++++++++++++----------------
1 files changed, 24 insertions(+), 16 deletions(-)
diff --git a/libavcodec/gifdec.c b/libavcodec/gifdec.c
index 2a61090..91139e1 100644
--- a/libavcodec/gifdec.c
+++ b/libavcodec/gifdec.c
@@ -31,6 +31,10 @@
#define GCE_DISPOSAL_INPLACE 1
#define GCE_DISPOSAL_BACKGROUND 2
#define GCE_DISPOSAL_RESTORE 3
+#define GIF_TRAILER 0x3b
+#define GIF_EXTENSION_INTRODUCER 0x21
+#define GIF_IMAGE_SEPARATOR 0x2c
+#define GIF_GCE_EXT_LABEL 0xf9
typedef struct GifState {
AVFrame picture;
@@ -170,7 +174,7 @@ static int gif_read_extension(GifState *s)
av_dlog(s->avctx, "ext_code=0x%x len=%d\n", ext_code, ext_len);
switch(ext_code) {
- case 0xf9:
+ case GIF_GCE_EXT_LABEL:
if (ext_len != 4)
goto discard_ext;
s->transparent_color_index = -1;
@@ -248,28 +252,32 @@ static int gif_read_header1(GifState *s)
return 0;
}
-static int gif_parse_next_image(GifState *s)
+static int gif_parse_next_image(GifState *s, int *got_picture)
{
+ int ret;
+ *got_picture = sizeof(AVPicture);
while (s->bytestream < s->bytestream_end) {
int code = bytestream_get_byte(&s->bytestream);
av_dlog(s->avctx, "code=%02x '%c'\n", code, code);
switch (code) {
- case ',':
+ case GIF_IMAGE_SEPARATOR:
return gif_read_image(s);
- case '!':
- if (gif_read_extension(s) < 0)
- return -1;
+ case GIF_EXTENSION_INTRODUCER:
+ if ((ret = gif_read_extension(s)) < 0)
+ return ret;
break;
- case ';':
+ case GIF_TRAILER:
/* end of image */
+ *got_picture = 0;
+ return 0;
default:
- /* error or erroneous EOF */
- return -1;
+ /* erroneous block label */
+ return AVERROR_INVALIDDATA;
}
}
- return -1;
+ return AVERROR_EOF;
}
static av_cold int gif_decode_init(AVCodecContext *avctx)
@@ -285,7 +293,7 @@ static av_cold int gif_decode_init(AVCodecContext *avctx)
return 0;
}
-static int gif_decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
+static int gif_decode_frame(AVCodecContext *avctx, void *data, int *got_picture, AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
@@ -299,8 +307,8 @@ static int gif_decode_frame(AVCodecContext *avctx, void *data, int *data_size, A
return ret;
avctx->pix_fmt = AV_PIX_FMT_PAL8;
- if (av_image_check_size(s->screen_width, s->screen_height, 0, avctx))
- return -1;
+ if ((ret = av_image_check_size(s->screen_width, s->screen_height, 0, avctx)) < 0)
+ return ret;
avcodec_set_dimensions(avctx, s->screen_width, s->screen_height);
if (s->picture.data[0])
@@ -310,12 +318,12 @@ static int gif_decode_frame(AVCodecContext *avctx, void *data, int *data_size, A
return ret;
}
s->image_palette = (uint32_t *)s->picture.data[1];
- ret = gif_parse_next_image(s);
+ ret = gif_parse_next_image(s, got_picture);
if (ret < 0)
return ret;
+ else if (*got_picture)
+ *picture = s->picture;
- *picture = s->picture;
- *data_size = sizeof(AVPicture);
return s->bytestream - buf;
}
--
1.7.2.5
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