mirror of
https://github.com/FFmpeg/FFmpeg.git
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225 lines
6.9 KiB
C
225 lines
6.9 KiB
C
/*
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* Media 100 decoder
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* Copyright (c) 2022 Paul B Mahol
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*
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* This file is part of FFmpeg.
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*
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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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*
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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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*
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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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*/
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/**
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* @file
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* Media 100 decoder.
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*/
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#include <inttypes.h>
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#include "libavutil/intreadwrite.h"
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#include "avcodec.h"
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#include "bytestream.h"
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#include "codec_internal.h"
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typedef struct Media100Context {
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AVCodecContext *avctx; // wrapper context for mjpegb
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AVPacket *pkt;
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} Media100Context;
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static av_cold int media100_decode_init(AVCodecContext *avctx)
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{
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Media100Context *ctx = avctx->priv_data;
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const AVCodec *codec;
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int ret;
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codec = avcodec_find_decoder(AV_CODEC_ID_MJPEGB);
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if (!codec)
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return AVERROR_BUG;
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ctx->avctx = avcodec_alloc_context3(codec);
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if (!ctx->avctx)
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return AVERROR(ENOMEM);
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ctx->avctx->thread_count = 1;
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ctx->avctx->flags = avctx->flags;
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ctx->avctx->flags2 = avctx->flags2;
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ctx->avctx->width = ctx->avctx->coded_width = avctx->width;
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ctx->avctx->height = ctx->avctx->coded_height = avctx->height;
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ret = avcodec_open2(ctx->avctx, codec, NULL);
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if (ret < 0)
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return ret;
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ctx->pkt = av_packet_alloc();
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if (!ctx->pkt)
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return AVERROR(ENOMEM);
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return 0;
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}
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static int media100_decode_frame(AVCodecContext *avctx,
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AVFrame *frame, int *got_frame,
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AVPacket *avpkt)
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{
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Media100Context *ctx = avctx->priv_data;
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unsigned second_field_offset = 0;
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unsigned next_field = 0;
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unsigned dht_offset[2];
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unsigned dqt_offset[2];
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unsigned sod_offset[2];
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unsigned sof_offset[2];
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unsigned sos_offset[2];
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unsigned field = 0;
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GetByteContext gb;
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PutByteContext pb;
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AVPacket *pkt;
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int ret;
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if (avpkt->size + 1024 > ctx->pkt->size) {
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ret = av_grow_packet(ctx->pkt, avpkt->size + 1024 - ctx->pkt->size);
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if (ret < 0)
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return ret;
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}
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ret = av_packet_make_writable(ctx->pkt);
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if (ret < 0)
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return ret;
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bytestream2_init(&gb, avpkt->data, avpkt->size);
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bytestream2_init_writer(&pb, ctx->pkt->data, ctx->pkt->size);
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second_field:
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bytestream2_put_be32(&pb, 0);
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bytestream2_put_be32(&pb, AV_RB32("mjpg"));
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bytestream2_put_be32(&pb, 0);
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bytestream2_put_be32(&pb, 0);
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for (int i = 0; i < 6; i++)
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bytestream2_put_be32(&pb, 0);
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sof_offset[field] = bytestream2_tell_p(&pb);
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bytestream2_put_be16(&pb, 17);
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bytestream2_put_byte(&pb, 8);
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bytestream2_put_be16(&pb, avctx->height / 2);
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bytestream2_put_be16(&pb, avctx->width);
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bytestream2_put_byte(&pb, 3);
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bytestream2_put_byte(&pb, 1);
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bytestream2_put_byte(&pb, 0x21);
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bytestream2_put_byte(&pb, 0);
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bytestream2_put_byte(&pb, 2);
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bytestream2_put_byte(&pb, 0x11);
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bytestream2_put_byte(&pb, 1);
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bytestream2_put_byte(&pb, 3);
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bytestream2_put_byte(&pb, 0x11);
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bytestream2_put_byte(&pb, 1);
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sos_offset[field] = bytestream2_tell_p(&pb);
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bytestream2_put_be16(&pb, 12);
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bytestream2_put_byte(&pb, 3);
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bytestream2_put_byte(&pb, 1);
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bytestream2_put_byte(&pb, 0);
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bytestream2_put_byte(&pb, 2);
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bytestream2_put_byte(&pb, 0x11);
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bytestream2_put_byte(&pb, 3);
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bytestream2_put_byte(&pb, 0x11);
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bytestream2_put_byte(&pb, 0);
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bytestream2_put_byte(&pb, 0);
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bytestream2_put_byte(&pb, 0);
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dqt_offset[field] = bytestream2_tell_p(&pb);
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bytestream2_put_be16(&pb, 132);
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bytestream2_put_byte(&pb, 0);
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bytestream2_skip(&gb, 4);
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for (int i = 0; i < 64; i++)
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bytestream2_put_byte(&pb, bytestream2_get_be32(&gb));
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bytestream2_put_byte(&pb, 1);
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for (int i = 0; i < 64; i++)
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bytestream2_put_byte(&pb, bytestream2_get_be32(&gb));
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dht_offset[field] = 0;
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sod_offset[field] = bytestream2_tell_p(&pb);
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for (int i = bytestream2_tell(&gb) + 8; next_field == 0 && i < avpkt->size - 4; i++) {
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if (AV_RB32(avpkt->data + i) == 0x00000001) {
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next_field = i;
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break;
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}
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}
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bytestream2_skip(&gb, 8);
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bytestream2_copy_buffer(&pb, &gb, next_field - bytestream2_tell(&gb));
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bytestream2_put_be64(&pb, 0);
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if (field == 0) {
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field = 1;
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second_field_offset = bytestream2_tell_p(&pb);
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next_field = avpkt->size;
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goto second_field;
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}
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pkt = ctx->pkt;
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AV_WB32(pkt->data + 8, second_field_offset);
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AV_WB32(pkt->data + 12, second_field_offset);
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AV_WB32(pkt->data + 16, second_field_offset);
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AV_WB32(pkt->data + 20, dqt_offset[0]);
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AV_WB32(pkt->data + 24, dht_offset[0]);
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AV_WB32(pkt->data + 28, sof_offset[0]);
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AV_WB32(pkt->data + 32, sos_offset[0]);
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AV_WB32(pkt->data + 36, sod_offset[0]);
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AV_WB32(pkt->data + second_field_offset + 8, bytestream2_tell_p(&pb) - second_field_offset);
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AV_WB32(pkt->data + second_field_offset + 12, bytestream2_tell_p(&pb) - second_field_offset);
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AV_WB32(pkt->data + second_field_offset + 16, 0);
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AV_WB32(pkt->data + second_field_offset + 20, dqt_offset[1] - second_field_offset);
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AV_WB32(pkt->data + second_field_offset + 24, dht_offset[1]);
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AV_WB32(pkt->data + second_field_offset + 28, sof_offset[1] - second_field_offset);
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AV_WB32(pkt->data + second_field_offset + 32, sos_offset[1] - second_field_offset);
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AV_WB32(pkt->data + second_field_offset + 36, sod_offset[1] - second_field_offset);
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pkt->size = bytestream2_tell_p(&pb);
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ret = avcodec_send_packet(ctx->avctx, pkt);
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if (ret < 0) {
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av_log(avctx, AV_LOG_ERROR, "Error submitting a packet for decoding\n");
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return ret;
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}
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ret = avcodec_receive_frame(ctx->avctx, frame);
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if (ret < 0)
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return ret;
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*got_frame = 1;
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return avpkt->size;
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}
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static av_cold int media100_decode_end(AVCodecContext *avctx)
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{
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Media100Context *ctx = avctx->priv_data;
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avcodec_free_context(&ctx->avctx);
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av_packet_free(&ctx->pkt);
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return 0;
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}
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const FFCodec ff_media100_decoder = {
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.p.name = "media100",
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CODEC_LONG_NAME("Media 100"),
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.p.type = AVMEDIA_TYPE_VIDEO,
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.p.id = AV_CODEC_ID_MEDIA100,
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.priv_data_size = sizeof(Media100Context),
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.init = media100_decode_init,
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.close = media100_decode_end,
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FF_CODEC_DECODE_CB(media100_decode_frame),
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.caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
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};
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