[FFmpeg-cvslog] avformat/gifdec: switch to using gif parser
Paul B Mahol
git at videolan.org
Thu May 25 20:56:44 EEST 2023
ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Sat May 20 14:13:27 2023 +0200| [c6b6356635f598b095606cd126f31bc6ab916225] | committer: Paul B Mahol
avformat/gifdec: switch to using gif parser
Update fate test, more correct as last packet is not truncated.
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=c6b6356635f598b095606cd126f31bc6ab916225
---
libavcodec/gifdec.c | 11 ++-
libavformat/gifdec.c | 247 ++++++++++++-----------------------------------
tests/ref/fate/gif-demux | 2 +-
3 files changed, 72 insertions(+), 188 deletions(-)
diff --git a/libavcodec/gifdec.c b/libavcodec/gifdec.c
index 0835c5bdd0..f2ab783ef0 100644
--- a/libavcodec/gifdec.c
+++ b/libavcodec/gifdec.c
@@ -472,10 +472,6 @@ static int gif_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
bytestream2_init(&s->gb, avpkt->data, avpkt->size);
- s->frame->pts = avpkt->pts;
- s->frame->pkt_dts = avpkt->dts;
- s->frame->duration = avpkt->duration;
-
if (avpkt->size >= 6) {
s->keyframe = memcmp(avpkt->data, gif87a_sig, 6) == 0 ||
memcmp(avpkt->data, gif89a_sig, 6) == 0;
@@ -522,6 +518,13 @@ static int gif_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
if ((ret = av_frame_ref(rframe, s->frame)) < 0)
return ret;
+ if (s->keyframe) {
+ rframe->pict_type = AV_PICTURE_TYPE_I;
+ rframe->flags |= AV_FRAME_FLAG_KEY;
+ } else {
+ rframe->pict_type = AV_PICTURE_TYPE_P;
+ rframe->flags &= ~AV_FRAME_FLAG_KEY;
+ }
*got_frame = 1;
return bytestream2_tell(&s->gb);
diff --git a/libavformat/gifdec.c b/libavformat/gifdec.c
index 1977f46e3a..774358e1fa 100644
--- a/libavformat/gifdec.c
+++ b/libavformat/gifdec.c
@@ -28,9 +28,12 @@
#include "libavutil/bprint.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/opt.h"
+#include "avio_internal.h"
#include "internal.h"
#include "libavcodec/gif.h"
+#define GIF_PACKET_SIZE 1024
+
typedef struct GIFDemuxContext {
const AVClass *class;
/**
@@ -53,9 +56,6 @@ typedef struct GIFDemuxContext {
int total_iter;
int iter_count;
int ignore_loop;
-
- int nb_frames;
- int last_duration;
} GIFDemuxContext;
/**
@@ -84,8 +84,8 @@ static int gif_probe(const AVProbeData *p)
static int resync(AVIOContext *pb)
{
- int i;
- for (i = 0; i < 6; i++) {
+ ffio_ensure_seekback(pb, 13);
+ for (int i = 0; i < 6; i++) {
int b = avio_r8(pb);
if (b != gif87a_sig[i] && b != gif89a_sig[i])
i = -(b != 'G');
@@ -113,11 +113,12 @@ static int gif_read_header(AVFormatContext *s)
AVIOContext *pb = s->pb;
AVStream *st;
int type, width, height, ret, n, flags;
- int64_t nb_frames = 0, duration = 0;
+ int64_t nb_frames = 0, duration = 0, pos;
if ((ret = resync(pb)) < 0)
return ret;
+ pos = avio_tell(pb);
gdc->delay = gdc->default_delay;
width = avio_rl16(pb);
height = avio_rl16(pb);
@@ -132,6 +133,9 @@ static int gif_read_header(AVFormatContext *s)
if (!st)
return AVERROR(ENOMEM);
+ if (!(pb->seekable & AVIO_SEEKABLE_NORMAL))
+ goto skip;
+
if (flags & 0x80)
avio_skip(pb, 3 * (1 << ((flags & 0x07) + 1)));
@@ -158,15 +162,37 @@ static int gif_read_header(AVFormatContext *s)
avio_skip(pb, 1);
delay = avio_rl16(pb);
- if (delay < gdc->min_delay)
- delay = gdc->default_delay;
- delay = FFMIN(delay, gdc->max_delay);
+ delay = delay ? delay : gdc->default_delay;
duration += delay;
avio_skip(pb, 1);
} else {
avio_skip(pb, block_size);
}
gif_skip_subblocks(pb);
+ } else if (subtype == GIF_APP_EXT_LABEL) {
+ uint8_t data[256];
+ int sb_size;
+
+ sb_size = avio_r8(pb);
+ ret = avio_read(pb, data, sb_size);
+ if (ret < 0 || !sb_size)
+ break;
+
+ if (sb_size == strlen(NETSCAPE_EXT_STR)) {
+ sb_size = avio_r8(pb);
+ ret = avio_read(pb, data, sb_size);
+ if (ret < 0 || !sb_size)
+ break;
+
+ if (sb_size == 3 && data[0] == 1) {
+ gdc->total_iter = AV_RL16(data+1);
+ av_log(s, AV_LOG_DEBUG, "Loop count is %d\n", gdc->total_iter);
+
+ if (gdc->total_iter == 0)
+ gdc->total_iter = -1;
+ }
+ }
+ gif_skip_subblocks(pb);
} else {
gif_skip_subblocks(pb);
}
@@ -183,203 +209,57 @@ static int gif_read_header(AVFormatContext *s)
}
}
+skip:
+ /* jump to start because gif decoder needs header data too */
+ if (avio_seek(pb, pos - 6, SEEK_SET) != pos - 6)
+ return AVERROR(EIO);
+
/* GIF format operates with time in "hundredths of second",
* therefore timebase is 1/100 */
avpriv_set_pts_info(st, 64, 1, 100);
+ ffstream(st)->need_parsing = AVSTREAM_PARSE_FULL_RAW;
st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
st->codecpar->codec_id = AV_CODEC_ID_GIF;
st->codecpar->width = width;
st->codecpar->height = height;
+ if (nb_frames > 1) {
+ av_reduce(&st->avg_frame_rate.num, &st->avg_frame_rate.den,
+ 100, duration / nb_frames, INT_MAX);
+ } else if (duration) {
+ st->avg_frame_rate = (AVRational) { 100, duration };
+ }
st->start_time = 0;
st->duration = duration;
st->nb_frames = nb_frames;
- if (n) {
- st->codecpar->sample_aspect_ratio.num = n + 15;
- st->codecpar->sample_aspect_ratio.den = 64;
- }
-
- /* jump to start because gif decoder needs header data too */
- if (avio_seek(pb, 0, SEEK_SET) != 0)
- return AVERROR(EIO);
+ if (n)
+ st->codecpar->sample_aspect_ratio = av_make_q(n + 15, 64);
return 0;
}
-static int gif_read_ext(AVFormatContext *s)
+static int gif_read_packet(AVFormatContext *s, AVPacket *pkt)
{
GIFDemuxContext *gdc = s->priv_data;
AVIOContext *pb = s->pb;
- int sb_size, ext_label = avio_r8(pb);
int ret;
- if (ext_label == GIF_GCE_EXT_LABEL) {
- if ((sb_size = avio_r8(pb)) < 4) {
- av_log(s, AV_LOG_FATAL, "Graphic Control Extension block's size less than 4.\n");
- return AVERROR_INVALIDDATA;
- }
-
- /* skip packed fields */
- if ((ret = avio_skip(pb, 1)) < 0)
- return ret;
-
- gdc->delay = avio_rl16(pb);
-
- if (gdc->delay < gdc->min_delay)
- gdc->delay = gdc->default_delay;
- gdc->delay = FFMIN(gdc->delay, gdc->max_delay);
-
- /* skip the rest of the Graphic Control Extension block */
- if ((ret = avio_skip(pb, sb_size - 3)) < 0 )
- return ret;
- } else if (ext_label == GIF_APP_EXT_LABEL) {
- uint8_t data[256];
-
- sb_size = avio_r8(pb);
- ret = avio_read(pb, data, sb_size);
- if (ret < 0 || !sb_size)
- return ret;
-
- if (sb_size == strlen(NETSCAPE_EXT_STR)) {
- sb_size = avio_r8(pb);
- ret = avio_read(pb, data, sb_size);
- if (ret < 0 || !sb_size)
- return ret;
-
- if (sb_size == 3 && data[0] == 1) {
- gdc->total_iter = AV_RL16(data+1);
- av_log(s, AV_LOG_DEBUG, "Loop count is %d\n", gdc->total_iter);
-
- if (gdc->total_iter == 0)
- gdc->total_iter = -1;
- }
- }
+ if ((pb->seekable & AVIO_SEEKABLE_NORMAL) &&
+ !gdc->ignore_loop && avio_feof(pb) &&
+ (gdc->total_iter < 0 || (++gdc->iter_count < gdc->total_iter))) {
+ avio_seek(pb, 0, SEEK_SET);
}
-
- if ((ret = gif_skip_subblocks(pb)) < 0)
+ if ((ret = av_new_packet(pkt, GIF_PACKET_SIZE)) < 0)
return ret;
- return 0;
-}
-
-static int gif_read_packet(AVFormatContext *s, AVPacket *pkt)
-{
- GIFDemuxContext *gdc = s->priv_data;
- AVIOContext *pb = s->pb;
- int packed_fields, block_label, ct_size,
- keyframe, frame_parsed = 0, ret;
- int64_t frame_start = avio_tell(pb), frame_end;
- unsigned char buf[6];
-
- if ((ret = avio_read(pb, buf, 6)) == 6) {
- keyframe = memcmp(buf, gif87a_sig, 6) == 0 ||
- memcmp(buf, gif89a_sig, 6) == 0;
- } else if (ret < 0) {
+ pkt->pos = avio_tell(pb);
+ pkt->stream_index = 0;
+ ret = avio_read_partial(pb, pkt->data, GIF_PACKET_SIZE);
+ if (ret < 0) {
+ av_packet_unref(pkt);
return ret;
- } else {
- keyframe = 0;
- }
-
- if (keyframe) {
-parse_keyframe:
- /* skip 2 bytes of width and 2 of height */
- if ((ret = avio_skip(pb, 4)) < 0)
- return ret;
-
- packed_fields = avio_r8(pb);
-
- /* skip 1 byte of Background Color Index and 1 byte of Pixel Aspect Ratio */
- if ((ret = avio_skip(pb, 2)) < 0)
- return ret;
-
- /* global color table presence */
- if (packed_fields & 0x80) {
- ct_size = 3 * (1 << ((packed_fields & 0x07) + 1));
-
- if ((ret = avio_skip(pb, ct_size)) < 0)
- return ret;
- }
- } else {
- avio_seek(pb, -ret, SEEK_CUR);
- ret = AVERROR_EOF;
- }
-
- while (GIF_TRAILER != (block_label = avio_r8(pb)) && !avio_feof(pb)) {
- if (block_label == GIF_EXTENSION_INTRODUCER) {
- if ((ret = gif_read_ext (s)) < 0 )
- goto resync;
- } else if (block_label == GIF_IMAGE_SEPARATOR) {
- /* skip to last byte of Image Descriptor header */
- if ((ret = avio_skip(pb, 8)) < 0)
- return ret;
-
- packed_fields = avio_r8(pb);
-
- /* local color table presence */
- if (packed_fields & 0x80) {
- ct_size = 3 * (1 << ((packed_fields & 0x07) + 1));
-
- if ((ret = avio_skip(pb, ct_size)) < 0)
- return ret;
- }
-
- /* read LZW Minimum Code Size */
- if (avio_r8(pb) < 1) {
- av_log(s, AV_LOG_ERROR, "lzw minimum code size must be >= 1\n");
- goto resync;
- }
-
- if ((ret = gif_skip_subblocks(pb)) < 0)
- goto resync;
-
- frame_end = avio_tell(pb);
-
- if (avio_seek(pb, frame_start, SEEK_SET) != frame_start)
- return AVERROR(EIO);
-
- ret = av_get_packet(pb, pkt, frame_end - frame_start);
- if (ret < 0)
- return ret;
-
- if (keyframe)
- pkt->flags |= AV_PKT_FLAG_KEY;
-
- pkt->stream_index = 0;
- pkt->duration = gdc->delay;
-
- gdc->nb_frames ++;
- gdc->last_duration = pkt->duration;
-
- /* Graphic Control Extension's scope is single frame.
- * Remove its influence. */
- gdc->delay = gdc->default_delay;
- frame_parsed = 1;
-
- break;
- } else {
- av_log(s, AV_LOG_ERROR, "invalid block label\n");
-resync:
- if (!keyframe)
- avio_seek(pb, frame_start, SEEK_SET);
- if ((ret = resync(pb)) < 0)
- return ret;
- frame_start = avio_tell(pb) - 6;
- keyframe = 1;
- goto parse_keyframe;
- }
}
-
- if ((ret >= 0 && !frame_parsed) || ret == AVERROR_EOF) {
- if (gdc->nb_frames == 1) {
- s->streams[0]->r_frame_rate = (AVRational) {100, gdc->last_duration};
- }
- /* This might happen when there is no image block
- * between extension blocks and GIF_TRAILER or EOF */
- if (!gdc->ignore_loop && (block_label == GIF_TRAILER || avio_feof(pb))
- && (gdc->total_iter < 0 || ++gdc->iter_count < gdc->total_iter))
- return avio_seek(pb, 0, SEEK_SET);
- return AVERROR_EOF;
- } else
- return ret;
+ av_shrink_packet(pkt, ret);
+ return ret;
}
static const AVOption options[] = {
@@ -405,6 +285,7 @@ const AVInputFormat ff_gif_demuxer = {
.read_probe = gif_probe,
.read_header = gif_read_header,
.read_packet = gif_read_packet,
- .flags = AVFMT_GENERIC_INDEX,
+ .flags = AVFMT_GENERIC_INDEX | AVFMT_NOTIMESTAMPS,
+ .extensions = "gif",
.priv_class = &demuxer_class,
};
diff --git a/tests/ref/fate/gif-demux b/tests/ref/fate/gif-demux
index 3d46441d8e..a3267a0d2a 100644
--- a/tests/ref/fate/gif-demux
+++ b/tests/ref/fate/gif-demux
@@ -38,4 +38,4 @@
0, 74, 74, 2, 4633, 0x8f64fda7, F=0x0
0, 76, 76, 2, 4700, 0x45f40805, F=0x0
0, 78, 78, 2, 5117, 0x4eb4c5fb, F=0x0
-0, 80, 80, 2, 5370, 0xb10c6910, F=0x0
+0, 80, 80, 2, 5371, 0x1a66694b, F=0x0
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