[FFmpeg-cvslog] avformat/gif: use first packet palette as global for PAL8
Clément Bœsch
git at videolan.org
Sat Feb 14 20:56:23 CET 2015
ffmpeg | branch: master | Clément Bœsch <u at pkh.me> | Fri Jan 23 16:34:14 2015 +0100| [5f9986f597e8a60d05b2f3fb63de5a423b82f9e3] | committer: Clément Bœsch
avformat/gif: use first packet palette as global for PAL8
This will allow the payload in PAL8 packets to not contain 768B of local
palette (which is not LZW compressed).
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5f9986f597e8a60d05b2f3fb63de5a423b82f9e3
---
libavformat/gif.c | 70 ++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 50 insertions(+), 20 deletions(-)
diff --git a/libavformat/gif.c b/libavformat/gif.c
index b4c5e8b..a729cc7 100644
--- a/libavformat/gif.c
+++ b/libavformat/gif.c
@@ -28,6 +28,28 @@
#include "libavutil/log.h"
#include "libavutil/opt.h"
+/* XXX: random value that shouldn't be taken into effect if there is no
+ * transparent color in the palette (the transparency bit will be set to 0) */
+#define DEFAULT_TRANSPARENCY_INDEX 0x1f
+
+static int get_palette_transparency_index(const uint32_t *palette)
+{
+ int transparent_color_index = -1;
+ unsigned i, smallest_alpha = 0xff;
+
+ if (!palette)
+ return -1;
+
+ for (i = 0; i < AVPALETTE_COUNT; i++) {
+ const uint32_t v = palette[i];
+ if (v >> 24 < smallest_alpha) {
+ smallest_alpha = v >> 24;
+ transparent_color_index = i;
+ }
+ }
+ return smallest_alpha < 128 ? transparent_color_index : -1;
+}
+
static int gif_image_write_header(AVIOContext *pb, const AVCodecContext *avctx,
int loop_count, uint32_t *palette)
{
@@ -47,8 +69,10 @@ static int gif_image_write_header(AVIOContext *pb, const AVCodecContext *avctx,
avio_wl16(pb, avctx->height);
if (palette) {
+ const int bcid = get_palette_transparency_index(palette);
+
avio_w8(pb, 0xf7); /* flags: global clut, 256 entries */
- avio_w8(pb, 0x1f); /* background color index */
+ avio_w8(pb, bcid < 0 ? DEFAULT_TRANSPARENCY_INDEX : bcid); /* background color index */
avio_w8(pb, aspect);
for (i = 0; i < 256; i++) {
const uint32_t v = palette[i] & 0xffffff;
@@ -73,6 +97,7 @@ static int gif_image_write_header(AVIOContext *pb, const AVCodecContext *avctx,
avio_w8(pb, 0x00); /* Data Sub-block Terminator */
}
+ avio_flush(pb);
return 0;
}
@@ -103,21 +128,20 @@ static int gif_write_header(AVFormatContext *s)
avpriv_set_pts_info(s->streams[0], 64, 1, 100);
if (avpriv_set_systematic_pal2(palette, video_enc->pix_fmt) < 0) {
av_assert0(video_enc->pix_fmt == AV_PIX_FMT_PAL8);
- gif_image_write_header(s->pb, video_enc, gif->loop, NULL);
+ /* delay header writing: we wait for the first palette to put it
+ * globally */
} else {
gif_image_write_header(s->pb, video_enc, gif->loop, palette);
}
- avio_flush(s->pb);
return 0;
}
static int flush_packet(AVFormatContext *s, AVPacket *new)
{
GIFContext *gif = s->priv_data;
- int size;
+ int size, bcid;
AVIOContext *pb = s->pb;
- uint8_t flags = 0x4, transparent_color_index = 0x1f;
const uint32_t *palette;
AVPacket *pkt = gif->prev_pkt;
@@ -131,19 +155,7 @@ static int flush_packet(AVFormatContext *s, AVPacket *new)
av_log(s, AV_LOG_ERROR, "Invalid palette extradata\n");
return AVERROR_INVALIDDATA;
}
- if (palette) {
- unsigned i, smallest_alpha = 0xff;
-
- for (i = 0; i < AVPALETTE_COUNT; i++) {
- const uint32_t v = palette[i];
- if (v >> 24 < smallest_alpha) {
- smallest_alpha = v >> 24;
- transparent_color_index = i;
- }
- }
- if (smallest_alpha < 128)
- flags |= 0x1; /* Transparent Color Flag */
- }
+ bcid = get_palette_transparency_index(palette);
if (new && new->pts != AV_NOPTS_VALUE)
gif->duration = av_clip_uint16(new->pts - gif->prev_pkt->pts);
@@ -154,9 +166,9 @@ static int flush_packet(AVFormatContext *s, AVPacket *new)
avio_w8(pb, 0x21);
avio_w8(pb, 0xf9);
avio_w8(pb, 0x04); /* block size */
- avio_w8(pb, flags);
+ avio_w8(pb, 1<<2 | (bcid >= 0));
avio_wl16(pb, gif->duration);
- avio_w8(pb, transparent_color_index);
+ avio_w8(pb, bcid < 0 ? DEFAULT_TRANSPARENCY_INDEX : bcid);
avio_w8(pb, 0x00);
avio_write(pb, pkt->data, pkt->size);
@@ -171,11 +183,29 @@ static int flush_packet(AVFormatContext *s, AVPacket *new)
static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
{
GIFContext *gif = s->priv_data;
+ const AVCodecContext *video_enc = s->streams[0]->codec;
if (!gif->prev_pkt) {
gif->prev_pkt = av_malloc(sizeof(*gif->prev_pkt));
if (!gif->prev_pkt)
return AVERROR(ENOMEM);
+
+ /* Write the first palette as global palette */
+ if (video_enc->pix_fmt == AV_PIX_FMT_PAL8) {
+ int size;
+ void *palette = av_packet_get_side_data(pkt, AV_PKT_DATA_PALETTE, &size);
+
+ if (!palette) {
+ av_log(s, AV_LOG_ERROR, "PAL8 packet is missing palette in extradata\n");
+ return AVERROR_INVALIDDATA;
+ }
+ if (size != AVPALETTE_SIZE) {
+ av_log(s, AV_LOG_ERROR, "Invalid palette extradata\n");
+ return AVERROR_INVALIDDATA;
+ }
+ gif_image_write_header(s->pb, video_enc, gif->loop, palette);
+ }
+
return av_copy_packet(gif->prev_pkt, pkt);
}
return flush_packet(s, pkt);
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