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