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FFmpeg/libavcodec/bsf/h264_redundant_pps.c

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/*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <inttypes.h>
#include "libavutil/log.h"
#include "bsf.h"
#include "bsf_internal.h"
#include "cbs.h"
#include "cbs_bsf.h"
#include "cbs_h264.h"
#include "codec_id.h"
#include "h264.h"
#include "packet.h"
#define NEW_GLOBAL_PIC_INIT_QP 26
typedef struct H264RedundantPPSContext {
CBSBSFContext common;
} H264RedundantPPSContext;
static int h264_redundant_pps_fixup_pps(H264RedundantPPSContext *ctx,
CodedBitstreamUnit *unit)
{
H264RawPPS *pps;
int err;
// The changes we are about to perform affect the parsing process,
// so we must make sure that the PPS is writable, otherwise the
// parsing of future slices will be incorrect and even raise errors.
err = ff_cbs_make_unit_writable(ctx->common.input, unit);
if (err < 0)
return err;
pps = unit->content;
// Overwrite pic_init_qp with the global value.
pps->pic_init_qp_minus26 = NEW_GLOBAL_PIC_INIT_QP - 26;
// Some PPSs have this set, so it must be set in all of them.
// (Slices which do not use such a PPS on input will still have
// *_weight_l*flag as zero and therefore write equivalently.)
pps->weighted_pred_flag = 1;
return 0;
}
static int h264_redundant_pps_fixup_slice(H264RedundantPPSContext *ctx,
H264RawSliceHeader *slice)
{
const CodedBitstreamH264Context *const in = ctx->common.input->priv_data;
const H264RawPPS *const pps = in->pps[slice->pic_parameter_set_id];
// We modified the PPS's qp value, now offset this by applying
// the negative offset to the slices.
slice->slice_qp_delta += pps->pic_init_qp_minus26
- (NEW_GLOBAL_PIC_INIT_QP - 26);
return 0;
}
static int h264_redundant_pps_update_fragment(AVBSFContext *bsf,
AVPacket *pkt,
CodedBitstreamFragment *au)
{
H264RedundantPPSContext *ctx = bsf->priv_data;
int err, i;
for (i = 0; i < au->nb_units; i++) {
CodedBitstreamUnit *nal = &au->units[i];
if (nal->type == H264_NAL_PPS) {
err = h264_redundant_pps_fixup_pps(ctx, nal);
if (err < 0)
return err;
}
if (nal->type == H264_NAL_SLICE ||
nal->type == H264_NAL_IDR_SLICE) {
H264RawSlice *slice = nal->content;
h264_redundant_pps_fixup_slice(ctx, &slice->header);
}
}
return 0;
}
static const CBSBSFType h264_redundant_pps_type = {
.codec_id = AV_CODEC_ID_H264,
.fragment_name = "access unit",
.unit_name = "NAL unit",
.update_fragment = &h264_redundant_pps_update_fragment,
};
static int h264_redundant_pps_init(AVBSFContext *bsf)
{
return ff_cbs_bsf_generic_init(bsf, &h264_redundant_pps_type);
}
static const enum AVCodecID h264_redundant_pps_codec_ids[] = {
AV_CODEC_ID_H264, AV_CODEC_ID_NONE,
};
const FFBitStreamFilter ff_h264_redundant_pps_bsf = {
.p.name = "h264_redundant_pps",
.p.codec_ids = h264_redundant_pps_codec_ids,
.priv_data_size = sizeof(H264RedundantPPSContext),
.init = &h264_redundant_pps_init,
.close = &ff_cbs_bsf_generic_close,
.filter = &ff_cbs_bsf_generic_filter,
};