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/*
* VP9 invisible (alt-ref) frame to superframe merge bitstream filter
* Copyright (c) 2016 Ronald S. Bultje <rsbultje@gmail.com>
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/avassert.h"
#include "avcodec.h"
#include "bitstream.h"
#include "bsf.h"
#define MAX_CACHE 8
typedef struct VP9BSFContext {
int n_cache;
AVPacket *cache[MAX_CACHE];
} VP9BSFContext;
static void stats(AVPacket * const *in, int n_in,
unsigned *_max, unsigned *_sum)
{
int n;
unsigned max = 0, sum = 0;
for (n = 0; n < n_in; n++) {
unsigned sz = in[n]->size;
if (sz > max)
max = sz;
sum += sz;
}
*_max = max;
*_sum = sum;
}
static int merge_superframe(AVPacket * const *in, int n_in, AVPacket *out)
{
unsigned max, sum, mag, marker, n, sz;
uint8_t *ptr;
int res;
stats(in, n_in, &max, &sum);
mag = av_log2(max) >> 3;
marker = 0xC0 + (mag << 3) + (n_in - 1);
sz = sum + 2 + (mag + 1) * n_in;
res = av_new_packet(out, sz);
if (res < 0)
return res;
ptr = out->data;
for (n = 0; n < n_in; n++) {
memcpy(ptr, in[n]->data, in[n]->size);
ptr += in[n]->size;
}
#define wloop(mag, wr) do { \
for (n = 0; n < n_in; n++) { \
wr; \
ptr += mag + 1; \
} \
} while (0)
// write superframe with marker 110[mag:2][nframes:3]
*ptr++ = marker;
switch (mag) {
case 0:
wloop(mag, *ptr = in[n]->size);
break;
case 1:
wloop(mag, AV_WL16(ptr, in[n]->size));
break;
case 2:
wloop(mag, AV_WL24(ptr, in[n]->size));
break;
case 3:
wloop(mag, AV_WL32(ptr, in[n]->size));
break;
}
*ptr++ = marker;
av_assert0(ptr == &out->data[out->size]);
return 0;
}
static int vp9_superframe_filter(AVBSFContext *ctx, AVPacket *out)
{
BitstreamContext bc;
VP9BSFContext *s = ctx->priv_data;
AVPacket *in;
int res, invisible, profile, marker, uses_superframe_syntax = 0, n;
res = ff_bsf_get_packet(ctx, &in);
if (res < 0)
return res;
marker = in->data[in->size - 1];
if ((marker & 0xe0) == 0xc0) {
int nbytes = 1 + ((marker >> 3) & 0x3);
int n_frames = 1 + (marker & 0x7), idx_sz = 2 + n_frames * nbytes;
uses_superframe_syntax = in->size >= idx_sz && in->data[in->size - idx_sz] == marker;
}
res = bitstream_init8(&bc, in->data, in->size);
if (res < 0)
goto done;
bitstream_read(&bc, 2); // frame marker
profile = bitstream_read(&bc, 1);
profile |= bitstream_read(&bc, 1) << 1;
if (profile == 3)
profile += bitstream_read(&bc, 1);
if (bitstream_read(&bc, 1)) {
invisible = 0;
} else {
bitstream_read(&bc, 1); // keyframe
invisible = !bitstream_read(&bc, 1);
}
if (uses_superframe_syntax && s->n_cache > 0) {
av_log(ctx, AV_LOG_ERROR,
"Mixing of superframe syntax and naked VP9 frames not supported");
res = AVERROR(ENOSYS);
goto done;
} else if ((!invisible || uses_superframe_syntax) && !s->n_cache) {
// passthrough
av_packet_move_ref(out, in);
goto done;
} else if (s->n_cache + 1 >= MAX_CACHE) {
av_log(ctx, AV_LOG_ERROR,
"Too many invisible frames");
res = AVERROR_INVALIDDATA;
goto done;
}
s->cache[s->n_cache++] = in;
in = NULL;
if (invisible) {
res = AVERROR(EAGAIN);
goto done;
}
av_assert0(s->n_cache > 0);
// build superframe
if ((res = merge_superframe(s->cache, s->n_cache, out)) < 0)
goto done;
res = av_packet_copy_props(out, s->cache[s->n_cache - 1]);
if (res < 0)
goto done;
for (n = 0; n < s->n_cache; n++)
av_packet_free(&s->cache[n]);
s->n_cache = 0;
done:
if (res < 0)
av_packet_unref(out);
av_packet_free(&in);
return res;
}
static void vp9_superframe_close(AVBSFContext *ctx)
{
VP9BSFContext *s = ctx->priv_data;
int n;
// free cached data
for (n = 0; n < s->n_cache; n++)
av_packet_free(&s->cache[n]);
}
static const enum AVCodecID codec_ids[] = {
AV_CODEC_ID_VP9, AV_CODEC_ID_NONE,
};
const AVBitStreamFilter ff_vp9_superframe_bsf = {
.name = "vp9_superframe",
.priv_data_size = sizeof(VP9BSFContext),
.filter = vp9_superframe_filter,
.close = vp9_superframe_close,
.codec_ids = codec_ids,
};
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