h264.c

video linux conference

            /* Parse the NAL */
            if( ( p_pic = ParseNALBlock( p_dec, p_part ) ) )
            {
                block_ChainAppend( &p_ret, p_pic );
            }
        }
        p += i_size;
    }

    return p_ret;
}

static block_t *nal_get_annexeb( decoder_t *p_dec, uint8_t *p, int i_size )
{
    block_t *p_nal;

    p_nal = block_New( p_dec, 3 + i_size );

    /* Add start code */
    p_nal->p_buffer[0] = 0x00;
    p_nal->p_buffer[1] = 0x00;
    p_nal->p_buffer[2] = 0x01;

    /* Copy nalu */
    memcpy( &p_nal->p_buffer[3], p, i_size );

    return p_nal;
}

static void nal_get_decoded( uint8_t **pp_ret, int *pi_ret,
                             uint8_t *src, int i_src )
{
    uint8_t *end = &src[i_src];
    uint8_t *dst = malloc( i_src );

    *pp_ret = dst;

    while( src < end )
    {
        if( src < end - 3 && src[0] == 0x00 && src[1] == 0x00 &&
            src[2] == 0x03 )
        {
            *dst++ = 0x00;
            *dst++ = 0x00;

            src += 3;
            continue;
        }
        *dst++ = *src++;
    }

    *pi_ret = dst - *pp_ret;
}

static inline int bs_read_ue( bs_t *s )
{
    int i = 0;

    while( bs_read1( s ) == 0 && s->p < s->p_end && i < 32 )
    {
        i++;
    }
    return( ( 1 << i) - 1 + bs_read( s, i ) );
}

static inline int bs_read_se( bs_t *s )
{
    int val = bs_read_ue( s );

    return val&0x01 ? (val+1)/2 : -(val/2);
}


static block_t *ParseNALBlock( decoder_t *p_dec, block_t *p_frag )
{
    decoder_sys_t *p_sys = p_dec->p_sys;
    block_t *p_pic = NULL;

    const int i_nal_ref_idc = (p_frag->p_buffer[3] >> 5)&0x03;
    const int i_nal_type = p_frag->p_buffer[3]&0x1f;

#define OUTPUT \
    do {                                                \
        p_pic = block_ChainGather( p_sys->p_frame );    \
        p_pic->i_length = 0;    /* FIXME */             \
                                                        \
        p_sys->p_frame = NULL;                          \
        p_sys->b_slice = VLC_FALSE;                     \
    } while(0)


    if( p_sys->b_slice && !p_sys->b_sps )
    {
        block_ChainRelease( p_sys->p_frame );
        msg_Warn( p_dec, "waiting for SPS" );

        /* Reset context */
        p_sys->p_frame = NULL;
        p_sys->b_slice = VLC_FALSE;
    }

    if( !p_sys->b_sps &&
        i_nal_type >= NAL_SLICE && i_nal_type <= NAL_SLICE_IDR )
    {
        p_sys->b_slice = VLC_TRUE;
        /* Fragment will be discarded later on */
    }
    else if( i_nal_type >= NAL_SLICE && i_nal_type <= NAL_SLICE_IDR )
    {
        uint8_t *dec;
        int i_dec, i_first_mb, i_slice_type, i_frame_num, i_pic_flags = 0;
        vlc_bool_t b_pic = VLC_FALSE;
        bs_t s;

        /* do not convert the whole frame */
        nal_get_decoded( &dec, &i_dec, &p_frag->p_buffer[4],
                         __MIN( p_frag->i_buffer - 4, 60 ) );
        bs_init( &s, dec, i_dec );

        /* first_mb_in_slice */
        i_first_mb = bs_read_ue( &s );

        /* slice_type */
        switch( (i_slice_type = bs_read_ue( &s )) )
        {
            case 0: case 5:
                i_pic_flags = BLOCK_FLAG_TYPE_P;
                break;
            case 1: case 6:
                i_pic_flags = BLOCK_FLAG_TYPE_B;
                break;
            case 2: case 7:
                i_pic_flags = BLOCK_FLAG_TYPE_I;
                break;
            case 3: case 8: /* SP */
                i_pic_flags = BLOCK_FLAG_TYPE_P;
                break;
            case 4: case 9:
                i_pic_flags = BLOCK_FLAG_TYPE_I;
                break;
        }

        /* pic_parameter_set_id */
        bs_read_ue( &s );
        /* frame_num */
        i_frame_num = bs_read( &s, p_sys->i_log2_max_frame_num + 4 );

        /* Detection of the first VCL NAL unit of a primary coded picture
         * (cf. 7.4.1.2.4) */
        if( i_frame_num != p_sys->i_frame_num ||
            ( (i_nal_ref_idc != p_sys->i_nal_ref_idc) &&
              (!i_nal_ref_idc || !p_sys->i_nal_ref_idc) ) )
        {
            b_pic = VLC_TRUE;
        }
        p_sys->i_frame_num = i_frame_num;
        p_sys->i_nal_ref_idc = i_nal_ref_idc;

        if( !p_sys->b_frame_mbs_only )
        {
            /* field_pic_flag */
            if( bs_read( &s, 1 ) )
            {
                /* bottom_field_flag */
                bs_read( &s, 1 );
            }
        }

        if( i_nal_type == NAL_SLICE_IDR )
        {
            /* id_pic_id */
            int i_idr_pic_id = bs_read_ue( &s );
            if( p_sys->i_nal_type != i_nal_type ) b_pic = VLC_TRUE;
            if( p_sys->i_idr_pic_id != i_idr_pic_id ) b_pic = VLC_TRUE;
            p_sys->i_idr_pic_id = i_idr_pic_id;
        }
        p_sys->i_nal_type = i_nal_type;

        if( b_pic && p_sys->b_slice )
            OUTPUT;

        p_sys->b_slice = VLC_TRUE;

        free( dec );
    }
    else if( i_nal_type == NAL_SPS )
    {
        uint8_t *dec;
        int     i_dec;
        bs_t s;
        int i_tmp;

        if( !p_sys->b_sps )
            msg_Dbg( p_dec, "found NAL_SPS" );

        p_sys->b_sps = VLC_TRUE;

        nal_get_decoded( &dec, &i_dec, &p_frag->p_buffer[4],
                         p_frag->i_buffer - 4 );

        bs_init( &s, dec, i_dec );
        /* Skip profile(8), constraint_set012, reserver(5), level(8) */
        bs_skip( &s, 8 + 1+1+1 + 5 + 8 );
        /* sps id */
        bs_read_ue( &s );
        /* Skip i_log2_max_frame_num */
        p_sys->i_log2_max_frame_num = bs_read_ue( &s );
        /* Read poc_type */
        i_tmp = bs_read_ue( &s );
        if( i_tmp == 0 )
        {
            /* skip i_log2_max_poc_lsb */
            bs_read_ue( &s );
        }
        else if( i_tmp == 1 )
        {
            int i_cycle;
            /* skip b_delta_pic_order_always_zero */
            bs_skip( &s, 1 );
            /* skip i_offset_for_non_ref_pic */
            bs_read_se( &s );
            /* skip i_offset_for_top_to_bottom_field */
            bs_read_se( &s );
            /* read i_num_ref_frames_in_poc_cycle */
            i_cycle = bs_read_ue( &s );
            if( i_cycle > 256 ) i_cycle = 256;
            while( i_cycle > 0 )
            {
                /* skip i_offset_for_ref_frame */
                bs_read_se(&s );
            }
        }
        /* i_num_ref_frames */
        bs_read_ue( &s );
        /* b_gaps_in_frame_num_value_allowed */
        bs_skip( &s, 1 );

        /* Read size */
        p_dec->fmt_out.video.i_width  = 16 * ( bs_read_ue( &s ) + 1 );
        p_dec->fmt_out.video.i_height = 16 * ( bs_read_ue( &s ) + 1 );

        /* b_frame_mbs_only */
        p_sys->b_frame_mbs_only = bs_read( &s, 1 );
        if( p_sys->b_frame_mbs_only == 0 )
        {
            bs_skip( &s, 1 );
        }
        /* b_direct8x8_inference */
        bs_skip( &s, 1 );

        /* crop */
        i_tmp = bs_read( &s, 1 );
        if( i_tmp )
        {
            /* left */
            bs_read_ue( &s );
            /* right */
            bs_read_ue( &s );
            /* top */
            bs_read_ue( &s );
            /* bottom */
            bs_read_ue( &s );
        }

        /* vui */
        i_tmp = bs_read( &s, 1 );
        if( i_tmp )
        {
            /* read the aspect ratio part if any FIXME check it */
            i_tmp = bs_read( &s, 1 );
            if( i_tmp )
            {
                static const struct { int w, h; } sar[14] =
                {
                    { 0,   0 }, { 1,   1 }, { 12, 11 }, { 10, 11 },
                    { 16, 11 }, { 40, 33 }, { 24, 11 }, { 20, 11 },
                    { 32, 11 }, { 80, 33 }, { 18, 11 }, { 15, 11 },
                    { 64, 33 }, { 160,99 },
                };
                int i_sar = bs_read( &s, 8 );
                int w, h;

                if( i_sar < 14 )
                {
                    w = sar[i_sar].w;
                    h = sar[i_sar].h;
                }
                else
                {
                    w = bs_read( &s, 16 );
                    h = bs_read( &s, 16 );
                }
                if( h != 0 )
                    p_dec->fmt_out.video.i_aspect =
                        VOUT_ASPECT_FACTOR * w / h * p_dec->fmt_out.video.i_width /
                        p_dec->fmt_out.video.i_height;
                else
                    p_dec->fmt_out.video.i_aspect = VOUT_ASPECT_FACTOR;
            }
        }

        free( dec );


        if( p_sys->b_slice )
            OUTPUT;
    }
    else if( i_nal_type == NAL_PPS )
    {
        bs_t s;
        bs_init( &s, &p_frag->p_buffer[4], p_frag->i_buffer - 4 );

        if( !p_sys->b_pps )
            msg_Dbg( p_dec, "found NAL_PPS" );
        p_sys->b_pps = VLC_TRUE;

        /* TODO */

        if( p_sys->b_slice )
            OUTPUT;
    }
    else if( i_nal_type == NAL_AU_DELIMITER ||
             i_nal_type == NAL_SEI ||
             ( i_nal_type >= 13 && i_nal_type <= 18 ) )
    {
        if( p_sys->b_slice )
            OUTPUT;
    }

#undef OUTPUT

    /* Append the block */
    block_ChainAppend( &p_sys->p_frame, p_frag );

    return p_pic;
}