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ffmpeg / libavcodec / mjpega_dump_header_bsf.c @ 2912e87a

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/*
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 * MJPEG A dump header bitstream filter
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 * Copyright (c) 2006 Baptiste Coudurier
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 *
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 * This file is part of Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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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 * MJPEG A dump header bitstream filter
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 * modifies bitstream to be decoded by quicktime
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 */
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#include "avcodec.h"
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#include "bytestream.h"
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#include "mjpeg.h"
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static int mjpega_dump_header(AVBitStreamFilterContext *bsfc, 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, int keyframe)
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{
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    uint8_t *poutbufp;
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    unsigned dqt = 0, dht = 0, sof0 = 0;
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    int i;
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    if (avctx->codec_id != CODEC_ID_MJPEG) {
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        av_log(avctx, AV_LOG_ERROR, "mjpega bitstream filter only applies to mjpeg codec\n");
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        return 0;
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    }
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    *poutbuf_size = 0;
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    *poutbuf = av_malloc(buf_size + 44 + FF_INPUT_BUFFER_PADDING_SIZE);
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    poutbufp = *poutbuf;
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    bytestream_put_byte(&poutbufp, 0xff);
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    bytestream_put_byte(&poutbufp, SOI);
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    bytestream_put_byte(&poutbufp, 0xff);
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    bytestream_put_byte(&poutbufp, APP1);
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    bytestream_put_be16(&poutbufp, 42); /* size */
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    bytestream_put_be32(&poutbufp, 0);
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    bytestream_put_buffer(&poutbufp, "mjpg", 4);
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    bytestream_put_be32(&poutbufp, buf_size + 44); /* field size */
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    bytestream_put_be32(&poutbufp, buf_size + 44); /* pad field size */
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    bytestream_put_be32(&poutbufp, 0);             /* next ptr */
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    for (i = 0; i < buf_size - 1; i++) {
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        if (buf[i] == 0xff) {
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            switch (buf[i + 1]) {
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            case DQT:  dqt  = i + 46; break;
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            case DHT:  dht  = i + 46; break;
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            case SOF0: sof0 = i + 46; break;
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            case SOS:
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                bytestream_put_be32(&poutbufp, dqt); /* quant off */
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                bytestream_put_be32(&poutbufp, dht); /* huff off */
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                bytestream_put_be32(&poutbufp, sof0); /* image off */
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                bytestream_put_be32(&poutbufp, i + 46); /* scan off */
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                bytestream_put_be32(&poutbufp, i + 46 + AV_RB16(buf + i + 2)); /* data off */
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                bytestream_put_buffer(&poutbufp, buf + 2, buf_size - 2); /* skip already written SOI */
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                *poutbuf_size = poutbufp - *poutbuf;
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                return 1;
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            case APP1:
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                if (i + 8 < buf_size && AV_RL32(buf + i + 8) == AV_RL32("mjpg")) {
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                    av_log(avctx, AV_LOG_ERROR, "bitstream already formatted\n");
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                    memcpy(*poutbuf, buf, buf_size);
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                    *poutbuf_size = buf_size;
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                    return 1;
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                }
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            }
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        }
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    }
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    av_freep(poutbuf);
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    av_log(avctx, AV_LOG_ERROR, "could not find SOS marker in bitstream\n");
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    return 0;
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}
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AVBitStreamFilter ff_mjpega_dump_header_bsf = {
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    "mjpegadump",
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    0,
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    mjpega_dump_header,
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};