It's defined in Section 5.2, used by netflix.
see http://download.opencontent.netflix.com/?prefix=AV1/Chimera/
---
libavformat/allformats.c | 1 +
libavformat/av1dec.c | 193 +++++++++++++++++++++++++++++++++++++--
2 files changed, 185 insertions(+), 9 deletions(-)
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index fd9e46e233..8eead5619d 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -75,6 +75,7 @@ extern AVOutputFormat ff_asf_stream_muxer;
extern AVInputFormat ff_au_demuxer;
extern AVOutputFormat ff_au_muxer;
extern AVInputFormat ff_av1_demuxer;
+extern AVInputFormat ff_av1_low_overhead_demuxer;
extern AVInputFormat ff_avi_demuxer;
extern AVOutputFormat ff_avi_muxer;
extern AVInputFormat ff_avisynth_demuxer;
diff --git a/libavformat/av1dec.c b/libavformat/av1dec.c
index ec66152e03..0c5d172a0f 100644
--- a/libavformat/av1dec.c
+++ b/libavformat/av1dec.c
@@ -28,6 +28,9 @@
#include "avio_internal.h"
#include "internal.h"
+//2 + max leb 128 size
+#define MAX_HEAD_SIZE 10
+
typedef struct AnnexBContext {
const AVClass *class;
AVBSFContext *bsf;
@@ -139,9 +142,8 @@ static int annexb_probe(const AVProbeData *p)
return 0;
}
-static int annexb_read_header(AVFormatContext *s)
+static int read_header(AVFormatContext *s, AVRational framerate, AVBSFContext
**bsf, void *c)
{
- AnnexBContext *c = s->priv_data;
const AVBitStreamFilter *filter = av_bsf_get_by_name("av1_frame_merge");
AVStream *st;
int ret;
@@ -160,25 +162,32 @@ static int annexb_read_header(AVFormatContext *s)
st->codecpar->codec_id = AV_CODEC_ID_AV1;
st->need_parsing = AVSTREAM_PARSE_HEADERS;
- st->internal->avctx->framerate = c->framerate;
+ st->internal->avctx->framerate = framerate;
// taken from rawvideo demuxers
avpriv_set_pts_info(st, 64, 1, 1200000);
- ret = av_bsf_alloc(filter, &c->bsf);
+ ret = av_bsf_alloc(filter, bsf);
if (ret < 0)
return ret;
- ret = avcodec_parameters_copy(c->bsf->par_in, st->codecpar);
+ ret = avcodec_parameters_copy((*bsf)->par_in, st->codecpar);
if (ret < 0) {
- av_bsf_free(&c->bsf);
+ av_bsf_free(bsf);
return ret;
}
- ret = av_bsf_init(c->bsf);
+ ret = av_bsf_init(*bsf);
if (ret < 0)
- av_bsf_free(&c->bsf);
+ av_bsf_free(bsf);
return ret;
+
+}
+
+static int annexb_read_header(AVFormatContext *s)
+{
+ AnnexBContext *c = s->priv_data;
+ return read_header(s, c->framerate, &c->bsf, c);
}
static int annexb_read_packet(AVFormatContext *s, AVPacket *pkt)
@@ -246,12 +255,158 @@ static int annexb_read_close(AVFormatContext *s)
return 0;
}
-#define OFFSET(x) offsetof(AnnexBContext, x)
+typedef struct LowOverheadContext {
+ const AVClass *class;
+ AVBSFContext *bsf;
+ AVRational framerate;
+ uint8_t prefetched[MAX_HEAD_SIZE];
+ //prefetched len
+ int len;
+} LowOverheadContext;
+
+static int low_overhead_probe(const AVProbeData *p)
+{
+ AVIOContext pb;
+ int64_t obu_size;
+ int ret, type, cnt = 0, has_size_flag;
+
+ ffio_init_context(&pb, p->buf, p->buf_size, 0,
+ NULL, NULL, NULL, NULL);
+
+ // Check that the first OBU is a Temporal Delimiter.
+ ret = read_obu(p->buf + cnt, FFMIN(p->buf_size - cnt, MAX_HEAD_SIZE),
&obu_size, &type, &has_size_flag);
+ if (ret < 0 || type != AV1_OBU_TEMPORAL_DELIMITER || obu_size != 0 ||
!has_size_flag)
+ return 0;
+ cnt += ret;
+
+ ret = read_obu(p->buf + cnt, FFMIN(p->buf_size - cnt, MAX_HEAD_SIZE),
&obu_size, &type, &has_size_flag);
+ if (ret < 0 || type != AV1_OBU_SEQUENCE_HEADER || !has_size_flag)
+ return 0;
+ cnt += ret;
+
+ ret = read_obu(p->buf + cnt, FFMIN(p->buf_size - cnt, MAX_HEAD_SIZE),
&obu_size, &type, &has_size_flag);
+ if (ret < 0 || (type != AV1_OBU_FRAME && type != AV1_OBU_FRAME_HEADER) ||
obu_size <= 0 || !has_size_flag)
+ return 0;
+ return AVPROBE_SCORE_EXTENSION + 1;
+}
+
+static int low_overhead_read_header(AVFormatContext *s)
+{
+ LowOverheadContext *c = s->priv_data;
+ return read_header(s, c->framerate, &c->bsf, c);
+}
+
+static int low_overhead_prefetch(AVFormatContext *s)
+{
+ LowOverheadContext *c = s->priv_data;
+ int ret;
+ int size = MAX_HEAD_SIZE - c->len;
+ if (size > 0 && !avio_feof(s->pb)) {
+ ret = avio_read(s->pb, &c->prefetched[c->len], size);
+ if (ret < 0)
+ return ret;
+ c->len += ret;
+ }
+ return c->len;
+}
+
+static int low_overhead_read_data(AVFormatContext *s, AVPacket *pkt, int size)
+{
+ int left;
+ LowOverheadContext *c = s->priv_data;
+ int ret = av_new_packet(pkt, size);
+ if (ret < 0) {
+ av_log(c, AV_LOG_ERROR, "Failed to allocate packet for obu\n");
+ return ret;
+ }
+ if (size <= c->len) {
+ memcpy(pkt->data, c->prefetched, size);
+
+ left = c->len - size;
+ memcpy(c->prefetched, c->prefetched + size, left);
+ c->len = left;
+ } else {
+ memcpy(pkt->data, c->prefetched, c->len);
+ left = size - c->len;
+ ret = avio_read(s->pb, pkt->data + c->len, left);
+ if (ret != left) {
+ av_log(c, AV_LOG_ERROR, "Failed to read %d frome file\n", left);
+ return ret;
+ }
+ c->len = 0;
+ }
+ return 0;
+}
+
+static int low_overhead_get_packet(AVFormatContext *s, AVPacket *pkt)
+{
+ int64_t obu_size;
+ int ret, type, has_size_flag;
+ LowOverheadContext *c = s->priv_data;
+ ret = low_overhead_prefetch(s);
+ if (ret < 0)
+ return ret;
+ if (ret) {
+ ret = read_obu(c->prefetched, c->len, &obu_size, &type,
&has_size_flag);
+ if (ret < 0 && !has_size_flag) {
+ av_log(c, AV_LOG_ERROR, "Failed to read obu\n");
+ return ret;
+ }
+ ret = low_overhead_read_data(s, pkt, ret);
+ }
+ return ret;
+}
+
+static int low_overhead_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+ LowOverheadContext *c = s->priv_data;
+ int ret;
+
+ while (1) {
+ ret = low_overhead_get_packet(s, pkt);
+ if (ret < 0)
+ return ret;
+ ret = av_bsf_send_packet(c->bsf, pkt);
+ if (ret < 0) {
+ av_log(s, AV_LOG_ERROR, "Failed to send packet to "
+ "av1_frame_merge filter\n");
+ return ret;
+ }
+ ret = av_bsf_receive_packet(c->bsf, pkt);
+ if (ret < 0 && ret != AVERROR(EAGAIN) && ret != AVERROR_EOF)
+ av_log(s, AV_LOG_ERROR, "av1_frame_merge filter failed to "
+ "send output packet\n");
+
+ if (ret != AVERROR(EAGAIN))
+ break;
+ }
+
+ return ret;
+}
+
+static int low_overhead_read_close(AVFormatContext *s)
+{
+ LowOverheadContext *c = s->priv_data;
+
+ av_bsf_free(&c->bsf);
+ return 0;
+}
+
#define DEC AV_OPT_FLAG_DECODING_PARAM
+
+#define OFFSET(x) offsetof(AnnexBContext, x)
static const AVOption annexb_options[] = {
{ "framerate", "", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str =
"25"}, 0, INT_MAX, DEC},
{ NULL },
};
+#undef OFFSET
+
+#define OFFSET(x) offsetof(LowOverheadContext, x)
+static const AVOption low_overhead_options[] = {
+ { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str =
"25"}, 0, INT_MAX, DEC},
+ { NULL },
+};
+#undef OFFSET
static const AVClass annexb_demuxer_class = {
.class_name = "AV1 Annex B demuxer",
@@ -272,3 +427,23 @@ AVInputFormat ff_av1_demuxer = {
.flags = AVFMT_GENERIC_INDEX,
.priv_class = &annexb_demuxer_class,
};
+
+static const AVClass low_overhead_demuxer_class = {
+ .class_name = "AV1 low overhead OBU demuxer",
+ .item_name = av_default_item_name,
+ .option = low_overhead_options,
+ .version = LIBAVUTIL_VERSION_INT,
+};
+
+AVInputFormat ff_av1_low_overhead_demuxer = {
+ .name = "av1",
+ .long_name = NULL_IF_CONFIG_SMALL("AV1 low overhead OBU"),
+ .priv_data_size = sizeof(LowOverheadContext),
+ .read_probe = low_overhead_probe,
+ .read_header = low_overhead_read_header,
+ .read_packet = low_overhead_read_packet,
+ .read_close = low_overhead_read_close,
+ .extensions = "obu",
+ .flags = AVFMT_GENERIC_INDEX,
+ .priv_class = &low_overhead_demuxer_class,
+};
--
2.17.1
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