parser.c

linux下的MPEG1

                    dprintf("skip %x\n", header);
                    /* reset free format frame size to give a chance
                       to get a new bitrate */
                    s->free_format_frame_size = 0;
                } else {
                    if((header&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
                        s->header_count= -3;
                    s->header= header;
                    s->header_count++;
                    s->frame_size = ret;

#if 0
                    /* free format: prepare to compute frame size */
                    if (decode_header(s, header) == 1) {
                        s->frame_size = -1;
                    }
#endif
                }
                if(s->header_count > 1)
                    avctx->sample_rate= sr;
            }
        } else
#if 0
        if (s->frame_size == -1) {
            /* free format : find next sync to compute frame size */
            len = MPA_MAX_CODED_FRAME_SIZE - len;
            if (len > buf_size)
                len = buf_size;
            if (len == 0) {
                /* frame too long: resync */
                s->frame_size = 0;
                memmove(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1);
                s->inbuf_ptr--;
            } else {
                uint8_t *p, *pend;
                uint32_t header1;
                int padding;

                memcpy(s->inbuf_ptr, buf_ptr, len);
                /* check for header */
                p = s->inbuf_ptr - 3;
                pend = s->inbuf_ptr + len - 4;
                while (p <= pend) {
                    header = (p[0] << 24) | (p[1] << 16) |
                        (p[2] << 8) | p[3];
                    header1 = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) |
                        (s->inbuf[2] << 8) | s->inbuf[3];
                    /* check with high probability that we have a
                       valid header */
                    if ((header & SAME_HEADER_MASK) ==
                        (header1 & SAME_HEADER_MASK)) {
                        /* header found: update pointers */
                        len = (p + 4) - s->inbuf_ptr;
                        buf_ptr += len;
                        buf_size -= len;
                        s->inbuf_ptr = p;
                        /* compute frame size */
                        s->free_format_next_header = header;
                        s->free_format_frame_size = s->inbuf_ptr - s->inbuf;
                        padding = (header1 >> 9) & 1;
                        if (s->layer == 1)
                            s->free_format_frame_size -= padding * 4;
                        else
                            s->free_format_frame_size -= padding;
                        dprintf("free frame size=%d padding=%d\n",
                                s->free_format_frame_size, padding);
                        decode_header(s, header1);
                        goto next_data;
                    }
                    p++;
                }
                /* not found: simply increase pointers */
                buf_ptr += len;
                s->inbuf_ptr += len;
                buf_size -= len;
            }
        } else
#endif
        if (len < s->frame_size) {
            if (s->frame_size > MPA_MAX_CODED_FRAME_SIZE)
                s->frame_size = MPA_MAX_CODED_FRAME_SIZE;
            len = FFMIN(s->frame_size - len, buf_size);
            memcpy(s->inbuf_ptr, buf_ptr, len);
            buf_ptr += len;
            s->inbuf_ptr += len;
            buf_size -= len;
        }

        if(s->frame_size > 0 && buf_ptr - buf == s->inbuf_ptr - s->inbuf
           && buf_size + buf_ptr - buf >= s->frame_size){
            if(s->header_count > 0){
                *poutbuf = buf;
                *poutbuf_size = s->frame_size;
            }
            buf_ptr = buf + s->frame_size;
            s->inbuf_ptr = s->inbuf;
            s->frame_size = 0;
            break;
        }

        //    next_data:
        if (s->frame_size > 0 &&
            (s->inbuf_ptr - s->inbuf) >= s->frame_size) {
            if(s->header_count > 0){
                *poutbuf = s->inbuf;
                *poutbuf_size = s->inbuf_ptr - s->inbuf;
            }
            s->inbuf_ptr = s->inbuf;
            s->frame_size = 0;
            break;
        }
    }
    return buf_ptr - buf;
}
#endif /* CONFIG_MPEGAUDIO_PARSER */

#if defined(CONFIG_AC3_PARSER) || defined(CONFIG_AAC_PARSER)
/* also used for ADTS AAC */
typedef struct AC3ParseContext {
    uint8_t *inbuf_ptr;
    int frame_size;
    int header_size;
    int (*sync)(const uint8_t *buf, int *channels, int *sample_rate,
                int *bit_rate, int *samples);
    uint8_t inbuf[8192]; /* input buffer */
} AC3ParseContext;

#define AC3_HEADER_SIZE 7
#define AAC_HEADER_SIZE 7

#ifdef CONFIG_AC3_PARSER
static const int ac3_sample_rates[4] = {
    48000, 44100, 32000, 0
};

static const int ac3_frame_sizes[64][3] = {
    { 64,   69,   96   },
    { 64,   70,   96   },
    { 80,   87,   120  },
    { 80,   88,   120  },
    { 96,   104,  144  },
    { 96,   105,  144  },
    { 112,  121,  168  },
    { 112,  122,  168  },
    { 128,  139,  192  },
    { 128,  140,  192  },
    { 160,  174,  240  },
    { 160,  175,  240  },
    { 192,  208,  288  },
    { 192,  209,  288  },
    { 224,  243,  336  },
    { 224,  244,  336  },
    { 256,  278,  384  },
    { 256,  279,  384  },
    { 320,  348,  480  },
    { 320,  349,  480  },
    { 384,  417,  576  },
    { 384,  418,  576  },
    { 448,  487,  672  },
    { 448,  488,  672  },
    { 512,  557,  768  },
    { 512,  558,  768  },
    { 640,  696,  960  },
    { 640,  697,  960  },
    { 768,  835,  1152 },
    { 768,  836,  1152 },
    { 896,  975,  1344 },
    { 896,  976,  1344 },
    { 1024, 1114, 1536 },
    { 1024, 1115, 1536 },
    { 1152, 1253, 1728 },
    { 1152, 1254, 1728 },
    { 1280, 1393, 1920 },
    { 1280, 1394, 1920 },
};

static const int ac3_bitrates[64] = {
    32, 32, 40, 40, 48, 48, 56, 56, 64, 64, 80, 80, 96, 96, 112, 112,
    128, 128, 160, 160, 192, 192, 224, 224, 256, 256, 320, 320, 384,
    384, 448, 448, 512, 512, 576, 576, 640, 640,
};

static const uint8_t ac3_channels[8] = {
    2, 1, 2, 3, 3, 4, 4, 5
};

static const uint8_t eac3_blocks[4] = {
    1, 2, 3, 6
};

#endif /* CONFIG_AC3_PARSER */

#ifdef CONFIG_AAC_PARSER
static const int aac_sample_rates[16] = {
    96000, 88200, 64000, 48000, 44100, 32000,
    24000, 22050, 16000, 12000, 11025, 8000, 7350
};

static const int aac_channels[8] = {
    0, 1, 2, 3, 4, 5, 6, 8
};
#endif

#ifdef CONFIG_AC3_PARSER
static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
                    int *bit_rate, int *samples)
{
    unsigned int fscod, frmsizecod, acmod, bsid, lfeon;
    unsigned int strmtyp, substreamid, frmsiz, fscod2, numblkscod;
    GetBitContext bits;

    init_get_bits(&bits, buf, AC3_HEADER_SIZE * 8);

    if(get_bits(&bits, 16) != 0x0b77)
        return 0;

    bsid = show_bits_long(&bits, 29) & 0x1f;
    if(bsid <= 8) {             /* Normal AC-3 */
        skip_bits(&bits, 16);       /* crc */
        fscod = get_bits(&bits, 2);
        frmsizecod = get_bits(&bits, 6);

        if(fscod == 3)
            return 0;

        skip_bits(&bits, 5);        /* bsid */
        skip_bits(&bits, 3);        /* bsmod */
        acmod = get_bits(&bits, 3);
        if(acmod & 1 && acmod != 1)
            skip_bits(&bits, 2);    /* cmixlev */
        if(acmod & 4)
            skip_bits(&bits, 2);    /* surmixlev */
        if(acmod & 2)
            skip_bits(&bits, 2);    /* dsurmod */
        lfeon = get_bits1(&bits);

        *sample_rate = ac3_sample_rates[fscod];
        *bit_rate = ac3_bitrates[frmsizecod] * 1000;
        *channels = ac3_channels[acmod] + lfeon;
        *samples = 6 * 256;

        return ac3_frame_sizes[frmsizecod][fscod] * 2;
    } else if (bsid >= 10 && bsid <= 16) { /* Enhanced AC-3 */
        strmtyp = get_bits(&bits, 2);
        substreamid = get_bits(&bits, 3);

        if (strmtyp != 0 || substreamid != 0)
            return 0;   /* Currently don't support additional streams */

        frmsiz = get_bits(&bits, 11) + 1;
        fscod = get_bits(&bits, 2);
        if (fscod == 3) {
            fscod2 = get_bits(&bits, 2);
            numblkscod = 3;

            if(fscod2 == 3)
                return 0;

            *sample_rate = ac3_sample_rates[fscod2] / 2;
        } else {
            numblkscod = get_bits(&bits, 2);

            *sample_rate = ac3_sample_rates[fscod];
        }

        acmod = get_bits(&bits, 3);
        lfeon = get_bits1(&bits);

        *samples = eac3_blocks[numblkscod] * 256;
        *bit_rate = frmsiz * (*sample_rate) * 16 / (*samples);
        *channels = ac3_channels[acmod] + lfeon;

        return frmsiz * 2;
    }

    /* Unsupported bitstream version */
    return 0;
}
#endif /* CONFIG_AC3_PARSER */

#ifdef CONFIG_AAC_PARSER
static int aac_sync(const uint8_t *buf, int *channels, int *sample_rate,
                    int *bit_rate, int *samples)
{
    GetBitContext bits;
    int size, rdb, ch, sr;

    init_get_bits(&bits, buf, AAC_HEADER_SIZE * 8);

    if(get_bits(&bits, 12) != 0xfff)
        return 0;

    skip_bits1(&bits);          /* id */
    skip_bits(&bits, 2);        /* layer */
    skip_bits1(&bits);          /* protection_absent */
    skip_bits(&bits, 2);        /* profile_objecttype */
    sr = get_bits(&bits, 4);    /* sample_frequency_index */
    if(!aac_sample_rates[sr])
        return 0;
    skip_bits1(&bits);          /* private_bit */
    ch = get_bits(&bits, 3);    /* channel_configuration */
    if(!aac_channels[ch])
        return 0;
    skip_bits1(&bits);          /* original/copy */
    skip_bits1(&bits);          /* home */

    /* adts_variable_header */
    skip_bits1(&bits);          /* copyright_identification_bit */
    skip_bits1(&bits);          /* copyright_identification_start */
    size = get_bits(&bits, 13); /* aac_frame_length */
    skip_bits(&bits, 11);       /* adts_buffer_fullness */
    rdb = get_bits(&bits, 2);   /* number_of_raw_data_blocks_in_frame */

    *channels = aac_channels[ch];
    *sample_rate = aac_sample_rates[sr];
    *samples = (rdb + 1) * 1024;
    *bit_rate = size * 8 * *sample_rate / *samples;

    return size;
}
#endif /* CONFIG_AAC_PARSER */

#ifdef CONFIG_AC3_PARSER
static int ac3_parse_init(AVCodecParserContext *s1)
{
    AC3ParseContext *s = s1->priv_data;
    s->inbuf_ptr = s->inbuf;
    s->header_size = AC3_HEADER_SIZE;
    s->sync = ac3_sync;
    return 0;
}
#endif

#ifdef CONFIG_AAC_PARSER
static int aac_parse_init(AVCodecParserContext *s1)
{
    AC3ParseContext *s = s1->priv_data;
    s->inbuf_ptr = s->inbuf;
    s->header_size = AAC_HEADER_SIZE;
    s->sync = aac_sync;
    return 0;
}
#endif

/* also used for ADTS AAC */
static int ac3_parse(AVCodecParserContext *s1,
                     AVCodecContext *avctx,
                     uint8_t **poutbuf, int *poutbuf_size,
                     const uint8_t *buf, int buf_size)
{
    AC3ParseContext *s = s1->priv_data;
    const uint8_t *buf_ptr;
    int len, sample_rate, bit_rate, channels, samples;

    *poutbuf = NULL;
    *poutbuf_size = 0;

    buf_ptr = buf;
    while (buf_size > 0) {
        len = s->inbuf_ptr - s->inbuf;
        if (s->frame_size == 0) {
            /* no header seen : find one. We need at least s->header_size
               bytes to parse it */
            len = FFMIN(s->header_size - len, buf_size);

            memcpy(s->inbuf_ptr, buf_ptr, len);
            buf_ptr += len;
            s->inbuf_ptr += len;
            buf_size -= len;
            if ((s->inbuf_ptr - s->inbuf) == s->header_size) {
                len = s->sync(s->inbuf, &channels, &sample_rate, &bit_rate,
                              &samples);
                if (len == 0) {
                    /* no sync found : move by one byte (inefficient, but simple!) */
                    memmove(s->inbuf, s->inbuf + 1, s->header_size - 1);
                    s->inbuf_ptr--;
                } else {
                    s->frame_size = len;
                    /* update codec info */
                    avctx->sample_rate = sample_rate;
                    /* set channels,except if the user explicitly requests 1 or 2 channels, XXX/FIXME this is a bit ugly */
                    if(avctx->codec_id == CODEC_ID_AC3){
                        if(avctx->channels!=1 && avctx->channels!=2){
                            avctx->channels = channels;
                        }
                    } else {
                        avctx->channels = channels;
                    }
                    avctx->bit_rate = bit_rate;
                    avctx->frame_size = samples;
                }
            }
        } else {
            len = FFMIN(s->frame_size - len, buf_size);

            memcpy(s->inbuf_ptr, buf_ptr, len);
            buf_ptr += len;
            s->inbuf_ptr += len;
            buf_size -= len;

            if(s->inbuf_ptr - s->inbuf == s->frame_size){
                *poutbuf = s->inbuf;
                *poutbuf_size = s->frame_size;
                s->inbuf_ptr = s->inbuf;
                s->frame_size = 0;
                break;
            }
        }
    }
    return buf_ptr - buf;
}
#endif /* CONFIG_AC3_PARSER || CONFIG_AAC_PARSER */

#ifdef CONFIG_MPEG4VIDEO_PARSER
AVCodecParser mpeg4video_parser = {
    { CODEC_ID_MPEG4 },
    sizeof(ParseContext1),
    mpeg4video_parse_init,
    mpeg4video_parse,
    ff_parse1_close,
    ff_mpeg4video_split,
};
#endif
#ifdef CONFIG_MPEGAUDIO_PARSER
AVCodecParser mpegaudio_parser = {
    { CODEC_ID_MP2, CODEC_ID_MP3 },
    sizeof(MpegAudioParseContext),
    mpegaudio_parse_init,
    mpegaudio_parse,
    NULL,
};
#endif
#ifdef CONFIG_AC3_PARSER
AVCodecParser ac3_parser = {
    { CODEC_ID_AC3 },
    sizeof(AC3ParseContext),
    ac3_parse_init,
    ac3_parse,
    NULL,
};
#endif
#ifdef CONFIG_AAC_PARSER
AVCodecParser aac_parser = {
    { CODEC_ID_AAC },
    sizeof(AC3ParseContext),
    aac_parse_init,
    ac3_parse,
    NULL,
};
#endif