parser.c

Go to the documentation of this file.

/*
 * Audio and Video frame extraction
 * Copyright (c) 2003 Fabrice Bellard
 * Copyright (c) 2003 Michael Niedermayer
 *
 * 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 <stdint.h>
#include <string.h>

#include "libavutil/avassert.h"
#include "libavutil/internal.h"
#include "libavutil/mem.h"

#include "internal.h"
#include "parser.h"

AVCodecParserContext *av_parser_init(int codec_id)
{
    AVCodecParserContext *s = NULL;
    const AVCodecParser *parser;
    void *i = 0;
    int ret;

    if (codec_id == AV_CODEC_ID_NONE)
        return NULL;

    while ((parser = av_parser_iterate(&i))) {
        if (parser->codec_ids[0] == codec_id ||
            parser->codec_ids[1] == codec_id ||
            parser->codec_ids[2] == codec_id ||
            parser->codec_ids[3] == codec_id ||
            parser->codec_ids[4] == codec_id)
            goto found;
    }
    return NULL;

found:
    s = av_mallocz(sizeof(AVCodecParserContext));
    if (!s)
        goto err_out;
    s->parser = (AVCodecParser*)parser;
    s->priv_data = av_mallocz(parser->priv_data_size);
    if (!s->priv_data)
        goto err_out;
    s->fetch_timestamp=1;
    s->pict_type = AV_PICTURE_TYPE_I;
    if (parser->parser_init) {
        ret = parser->parser_init(s);
        if (ret != 0)
            goto err_out;
    }
    s->key_frame            = -1;
#if FF_API_CONVERGENCE_DURATION
FF_DISABLE_DEPRECATION_WARNINGS
    s->convergence_duration = 0;
FF_ENABLE_DEPRECATION_WARNINGS
#endif
    s->dts_sync_point       = INT_MIN;
    s->dts_ref_dts_delta    = INT_MIN;
    s->pts_dts_delta        = INT_MIN;
    s->format               = -1;

    return s;

err_out:
    if (s)
        av_freep(&s->priv_data);
    av_free(s);
    return NULL;
}

void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove, int fuzzy)
{
    int i;

    if (!fuzzy) {
        s->dts    =
        s->pts    = AV_NOPTS_VALUE;
        s->pos    = -1;
        s->offset = 0;
    }
    for (i = 0; i < AV_PARSER_PTS_NB; i++) {
        if (s->cur_offset + off >= s->cur_frame_offset[i] &&
            (s->frame_offset < s->cur_frame_offset[i] ||
             (!s->frame_offset && !s->next_frame_offset)) && // first field/frame
            // check disabled since MPEG-TS does not send complete PES packets
            /*s->next_frame_offset + off <*/  s->cur_frame_end[i]){

            if (!fuzzy || s->cur_frame_dts[i] != AV_NOPTS_VALUE) {
                s->dts    = s->cur_frame_dts[i];
                s->pts    = s->cur_frame_pts[i];
                s->pos    = s->cur_frame_pos[i];
                s->offset = s->next_frame_offset - s->cur_frame_offset[i];
            }
            if (remove)
                s->cur_frame_offset[i] = INT64_MAX;
            if (s->cur_offset + off < s->cur_frame_end[i])
                break;
        }
    }
}

int av_parser_parse2(AVCodecParserContext *s, AVCodecContext *avctx,
                     uint8_t **poutbuf, int *poutbuf_size,
                     const uint8_t *buf, int buf_size,
                     int64_t pts, int64_t dts, int64_t pos)
{
    int index, i;
    uint8_t dummy_buf[AV_INPUT_BUFFER_PADDING_SIZE];

    av_assert1(avctx->codec_id != AV_CODEC_ID_NONE);

    /* Parsers only work for the specified codec ids. */
    av_assert1(avctx->codec_id == s->parser->codec_ids[0] ||
               avctx->codec_id == s->parser->codec_ids[1] ||
               avctx->codec_id == s->parser->codec_ids[2] ||
               avctx->codec_id == s->parser->codec_ids[3] ||
               avctx->codec_id == s->parser->codec_ids[4]);

    if (!(s->flags & PARSER_FLAG_FETCHED_OFFSET)) {
        s->next_frame_offset =
        s->cur_offset        = pos;
        s->flags            |= PARSER_FLAG_FETCHED_OFFSET;
    }

    if (buf_size == 0) {
        /* padding is always necessary even if EOF, so we add it here */
        memset(dummy_buf, 0, sizeof(dummy_buf));
        buf = dummy_buf;
    } else if (s->cur_offset + buf_size != s->cur_frame_end[s->cur_frame_start_index]) { /* skip remainder packets */
        /* add a new packet descriptor */
        i = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
        s->cur_frame_start_index = i;
        s->cur_frame_offset[i]   = s->cur_offset;
        s->cur_frame_end[i]      = s->cur_offset + buf_size;
        s->cur_frame_pts[i]      = pts;
        s->cur_frame_dts[i]      = dts;
        s->cur_frame_pos[i]      = pos;
    }

    if (s->fetch_timestamp) {
        s->fetch_timestamp = 0;
        s->last_pts        = s->pts;
        s->last_dts        = s->dts;
        s->last_pos        = s->pos;
        ff_fetch_timestamp(s, 0, 0, 0);
    }
    /* WARNING: the returned index can be negative */
    index = s->parser->parser_parse(s, avctx, (const uint8_t **) poutbuf,
                                    poutbuf_size, buf, buf_size);
    av_assert0(index > -0x20000000); // The API does not allow returning AVERROR codes
#define FILL(name) if(s->name > 0 && avctx->name <= 0) avctx->name = s->name
    if (avctx->codec_type == AVMEDIA_TYPE_VIDEO) {
        FILL(field_order);
    }

    /* update the file pointer */
    if (*poutbuf_size) {
        /* fill the data for the current frame */
        s->frame_offset = s->next_frame_offset;

        /* offset of the next frame */
        s->next_frame_offset = s->cur_offset + index;
        s->fetch_timestamp   = 1;
    }
    if (index < 0)
        index = 0;
    s->cur_offset += index;
    return index;
}

int av_parser_change(AVCodecParserContext *s, AVCodecContext *avctx,
                     uint8_t **poutbuf, int *poutbuf_size,
                     const uint8_t *buf, int buf_size, int keyframe)
{
    if (s && s->parser->split) {
        if (avctx->flags  & AV_CODEC_FLAG_GLOBAL_HEADER ||
            avctx->flags2 & AV_CODEC_FLAG2_LOCAL_HEADER) {
            int i = s->parser->split(avctx, buf, buf_size);
            buf      += i;
            buf_size -= i;
        }
    }

    /* cast to avoid warning about discarding qualifiers */
    *poutbuf      = (uint8_t *) buf;
    *poutbuf_size = buf_size;
    if (avctx->extradata) {
        if (keyframe && (avctx->flags2 & AV_CODEC_FLAG2_LOCAL_HEADER)) {
            int size = buf_size + avctx->extradata_size;

            *poutbuf_size = size;
            *poutbuf      = av_malloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
            if (!*poutbuf)
                return AVERROR(ENOMEM);

            memcpy(*poutbuf, avctx->extradata, avctx->extradata_size);
            memcpy(*poutbuf + avctx->extradata_size, buf,
                   buf_size + AV_INPUT_BUFFER_PADDING_SIZE);
            return 1;
        }
    }

    return 0;
}

void av_parser_close(AVCodecParserContext *s)
{
    if (s) {
        if (s->parser->parser_close)
            s->parser->parser_close(s);
        av_freep(&s->priv_data);
        av_free(s);
    }
}

int ff_combine_frame(ParseContext *pc, int next,
                     const uint8_t **buf, int *buf_size)
{
    if (pc->overread) {
        ff_dlog(NULL, "overread %d, state:%"PRIX32" next:%d index:%d o_index:%d\n",
                pc->overread, pc->state, next, pc->index, pc->overread_index);
        ff_dlog(NULL, "%X %X %X %X\n",
                (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
    }

    /* Copy overread bytes from last frame into buffer. */
    for (; pc->overread > 0; pc->overread--)
        pc->buffer[pc->index++] = pc->buffer[pc->overread_index++];

    /* flush remaining if EOF */
    if (!*buf_size && next == END_NOT_FOUND)
        next = 0;

    pc->last_index = pc->index;

    /* copy into buffer end return */
    if (next == END_NOT_FOUND) {
        void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
                                           *buf_size + pc->index +
                                           AV_INPUT_BUFFER_PADDING_SIZE);

        if (!new_buffer) {
            av_log(NULL, AV_LOG_ERROR, "Failed to reallocate parser buffer to %d\n", *buf_size + pc->index + AV_INPUT_BUFFER_PADDING_SIZE);
            pc->index = 0;
            return AVERROR(ENOMEM);
        }
        pc->buffer = new_buffer;
        memcpy(&pc->buffer[pc->index], *buf, *buf_size);
        pc->index += *buf_size;
        return -1;
    }

    av_assert0(next >= 0 || pc->buffer);

    *buf_size          =
    pc->overread_index = pc->index + next;

    /* append to buffer */
    if (pc->index) {
        void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
                                           next + pc->index +
                                           AV_INPUT_BUFFER_PADDING_SIZE);
        if (!new_buffer) {
            av_log(NULL, AV_LOG_ERROR, "Failed to reallocate parser buffer to %d\n", next + pc->index + AV_INPUT_BUFFER_PADDING_SIZE);
            pc->overread_index =
            pc->index = 0;
            return AVERROR(ENOMEM);
        }
        pc->buffer = new_buffer;
        if (next > -AV_INPUT_BUFFER_PADDING_SIZE)
            memcpy(&pc->buffer[pc->index], *buf,
                   next + AV_INPUT_BUFFER_PADDING_SIZE);
        pc->index = 0;
        *buf      = pc->buffer;
    }

    /* store overread bytes */
    for (; next < 0; next++) {
        pc->state   = pc->state   << 8 | pc->buffer[pc->last_index + next];
        pc->state64 = pc->state64 << 8 | pc->buffer[pc->last_index + next];
        pc->overread++;
    }

    if (pc->overread) {
        ff_dlog(NULL, "overread %d, state:%"PRIX32" next:%d index:%d o_index:%d\n",
                pc->overread, pc->state, next, pc->index, pc->overread_index);
        ff_dlog(NULL, "%X %X %X %X\n",
                (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
    }

    return 0;
}

void ff_parse_close(AVCodecParserContext *s)
{
    ParseContext *pc = s->priv_data;

    av_freep(&pc->buffer);
}

int ff_mpeg4video_split(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
{
    uint32_t state = -1;
    const uint8_t *ptr = buf, *end = buf + buf_size;

    while (ptr < end) {
        ptr = avpriv_find_start_code(ptr, end, &state);
        if (state == 0x1B3 || state == 0x1B6)
            return ptr - 4 - buf;
    }

    return 0;
}