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* H.264 MP4 to Annex B byte stream format filter
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* Copyright (c) 2007 Benoit Fouet <benoit.fouet@free.fr>
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* This file is part of FFmpeg.
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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#include "libavutil/intreadwrite.h"
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typedef struct H264BSFContext {
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uint8_t *sps_pps_data;
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static void alloc_and_copy(uint8_t **poutbuf, int *poutbuf_size,
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const uint8_t *sps_pps, uint32_t sps_pps_size,
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const uint8_t *in, uint32_t in_size) {
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uint32_t offset = *poutbuf_size;
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uint8_t nal_header_size = offset ? 3 : 4;
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*poutbuf_size += sps_pps_size+in_size+nal_header_size;
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*poutbuf = av_realloc(*poutbuf, *poutbuf_size);
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memcpy(*poutbuf+offset, sps_pps, sps_pps_size);
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memcpy(*poutbuf+sps_pps_size+nal_header_size+offset, in, in_size);
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AV_WB32(*poutbuf+sps_pps_size, 1);
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(*poutbuf+offset+sps_pps_size)[0] = (*poutbuf+offset+sps_pps_size)[1] = 0;
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(*poutbuf+offset+sps_pps_size)[2] = 1;
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static int h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
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AVCodecContext *avctx, const char *args,
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uint8_t **poutbuf, int *poutbuf_size,
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const uint8_t *buf, int buf_size,
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H264BSFContext *ctx = bsfc->priv_data;
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uint32_t cumul_size = 0;
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const uint8_t *buf_end = buf + buf_size;
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/* nothing to filter */
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if (!avctx->extradata || avctx->extradata_size < 6) {
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*poutbuf = (uint8_t*) buf;
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*poutbuf_size = buf_size;
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/* retrieve sps and pps NAL units from extradata */
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if (!ctx->sps_pps_data) {
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uint32_t total_size = 0;
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uint8_t *out = NULL, unit_nb, sps_done = 0;
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const uint8_t *extradata = avctx->extradata+4;
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static const uint8_t nalu_header[4] = {0, 0, 0, 1};
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/* retrieve length coded size */
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ctx->length_size = (*extradata++ & 0x3) + 1;
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if (ctx->length_size == 3)
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return AVERROR(EINVAL);
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/* retrieve sps and pps unit(s) */
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unit_nb = *extradata++ & 0x1f; /* number of sps unit(s) */
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unit_nb = *extradata++; /* number of pps unit(s) */
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unit_size = AV_RB16(extradata);
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total_size += unit_size+4;
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if (extradata+2+unit_size > avctx->extradata+avctx->extradata_size) {
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return AVERROR(EINVAL);
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out = av_realloc(out, total_size);
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return AVERROR(ENOMEM);
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memcpy(out+total_size-unit_size-4, nalu_header, 4);
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memcpy(out+total_size-unit_size, extradata+2, unit_size);
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extradata += 2+unit_size;
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if (!unit_nb && !sps_done++)
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unit_nb = *extradata++; /* number of pps unit(s) */
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ctx->sps_pps_data = out;
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ctx->size = total_size;
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if (buf + ctx->length_size > buf_end)
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if (ctx->length_size == 1)
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else if (ctx->length_size == 2)
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nal_size = AV_RB16(buf);
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nal_size = AV_RB32(buf);
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buf += ctx->length_size;
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unit_type = *buf & 0x1f;
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if (buf + nal_size > buf_end || nal_size < 0)
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/* prepend only to the first type 5 NAL unit of an IDR picture */
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if (ctx->first_idr && unit_type == 5) {
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alloc_and_copy(poutbuf, poutbuf_size,
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ctx->sps_pps_data, ctx->size,
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alloc_and_copy(poutbuf, poutbuf_size,
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if (!ctx->first_idr && unit_type == 1)
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cumul_size += nal_size + ctx->length_size;
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} while (cumul_size < buf_size);
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return AVERROR(EINVAL);
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static void h264_mp4toannexb_close(AVBitStreamFilterContext *bsfc)
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H264BSFContext *ctx = bsfc->priv_data;
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av_freep(&ctx->sps_pps_data);
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AVBitStreamFilter h264_mp4toannexb_bsf = {
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sizeof(H264BSFContext),
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h264_mp4toannexb_filter,
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h264_mp4toannexb_close,