stream.c

VLC Player Source Code

    /* Fill enough data */
    while( p_sys->block.i_size - (p_sys->i_pos - p_sys->block.i_start)
           < i_read )
    {
        block_t **pp_last = p_sys->block.pp_last;

        if( AStreamRefillBlock( s ) ) break;

        /* Our buffer are probably filled enough, don't try anymore */
        if( pp_last == p_sys->block.pp_last ) break;
    }

    /* Copy what we have */
    b = p_sys->block.p_current;
    i_offset = p_sys->block.i_offset;
    p_data = p_sys->p_peek;

    while( b && i_data < i_read )
    {
        unsigned int i_current = __MAX(b->i_buffer - i_offset,0);
        int i_copy = __MIN( i_current, i_read - i_data );

        memcpy( p_data, &b->p_buffer[i_offset], i_copy );
        i_data += i_copy;
        p_data += i_copy;
        i_offset += i_copy;

        if( i_offset >= b->i_buffer )
        {
            i_offset = 0;
            b = b->p_next;
        }
    }

    *pp_peek = p_sys->p_peek;
    return i_data;
}

static int AStreamSeekBlock( stream_t *s, int64_t i_pos )
{
    stream_sys_t *p_sys = s->p_sys;
    access_t   *p_access = p_sys->p_access;
    int64_t    i_offset = i_pos - p_sys->block.i_start;
    bool b_seek;

    /* We already have thoses data, just update p_current/i_offset */
    if( i_offset >= 0 && i_offset < p_sys->block.i_size )
    {
        block_t *b = p_sys->block.p_first;
        int i_current = 0;

        while( i_current + b->i_buffer < i_offset )
        {
            i_current += b->i_buffer;
            b = b->p_next;
        }

        p_sys->block.p_current = b;
        p_sys->block.i_offset = i_offset - i_current;

        p_sys->i_pos = i_pos;

        return VLC_SUCCESS;
    }

    /* We may need to seek or to read data */
    if( i_offset < 0 )
    {
        bool b_aseek;
        access_Control( p_access, ACCESS_CAN_SEEK, &b_aseek );

        if( !b_aseek )
        {
            msg_Err( s, "backward seeking impossible (access not seekable)" );
            return VLC_EGENERIC;
        }

        b_seek = true;
    }
    else
    {
        bool b_aseek, b_aseekfast;

        access_Control( p_access, ACCESS_CAN_SEEK, &b_aseek );
        access_Control( p_access, ACCESS_CAN_FASTSEEK, &b_aseekfast );

        if( !b_aseek )
        {
            b_seek = false;
            msg_Warn( s, "%"PRId64" bytes need to be skipped "
                      "(access non seekable)",
                      i_offset - p_sys->block.i_size );
        }
        else
        {
            int64_t i_skip = i_offset - p_sys->block.i_size;

            /* Avg bytes per packets */
            int i_avg = p_sys->stat.i_bytes / p_sys->stat.i_read_count;
            /* TODO compute a seek cost instead of fixed threshold */
            int i_th = b_aseekfast ? 1 : 5;

            if( i_skip <= i_th * i_avg &&
                i_skip < STREAM_CACHE_SIZE )
                b_seek = false;
            else
                b_seek = true;

            msg_Dbg( s, "b_seek=%d th*avg=%d skip=%"PRId64,
                     b_seek, i_th*i_avg, i_skip );
        }
    }

    if( b_seek )
    {
        int64_t i_start, i_end;
        /* Do the access seek */
        i_start = mdate();
        if( ASeek( s, i_pos ) ) return VLC_EGENERIC;
        i_end = mdate();

        /* Release data */
        block_ChainRelease( p_sys->block.p_first );

        /* Reinit */
        p_sys->block.i_start = p_sys->i_pos = i_pos;
        p_sys->block.i_offset = 0;
        p_sys->block.p_current = NULL;
        p_sys->block.i_size = 0;
        p_sys->block.p_first = NULL;
        p_sys->block.pp_last = &p_sys->block.p_first;

        /* Refill a block */
        if( AStreamRefillBlock( s ) )
            return VLC_EGENERIC;

        /* Update stat */
        p_sys->stat.i_seek_time += i_end - i_start;
        p_sys->stat.i_seek_count++;
        return VLC_SUCCESS;
    }
    else
    {
        do
        {
            /* Read and skip enough data */
            if( AStreamRefillBlock( s ) )
                return VLC_EGENERIC;

            while( p_sys->block.p_current &&
                   p_sys->i_pos + p_sys->block.p_current->i_buffer - p_sys->block.i_offset < i_pos )
            {
                p_sys->i_pos += p_sys->block.p_current->i_buffer - p_sys->block.i_offset;
                p_sys->block.p_current = p_sys->block.p_current->p_next;
                p_sys->block.i_offset = 0;
            }
        }
        while( p_sys->block.i_start + p_sys->block.i_size < i_pos );

        p_sys->block.i_offset = i_pos - p_sys->i_pos;
        p_sys->i_pos = i_pos;

        return VLC_SUCCESS;
    }

    return VLC_EGENERIC;
}

static int AStreamRefillBlock( stream_t *s )
{
    stream_sys_t *p_sys = s->p_sys;
    int64_t      i_start, i_stop;
    block_t      *b;

    /* Release data */
    while( p_sys->block.i_size >= STREAM_CACHE_SIZE &&
           p_sys->block.p_first != p_sys->block.p_current )
    {
        block_t *b = p_sys->block.p_first;

        p_sys->block.i_start += b->i_buffer;
        p_sys->block.i_size  -= b->i_buffer;
        p_sys->block.p_first  = b->p_next;

        block_Release( b );
    }
    if( p_sys->block.i_size >= STREAM_CACHE_SIZE &&
        p_sys->block.p_current == p_sys->block.p_first &&
        p_sys->block.p_current->p_next )    /* At least 2 packets */
    {
        /* Enough data, don't read more */
        return VLC_SUCCESS;
    }

    /* Now read a new block */
    i_start = mdate();
    for( ;; )
    {
        bool b_eof;

        if( s->b_die ) return VLC_EGENERIC;


        /* Fetch a block */
        if( ( b = AReadBlock( s, &b_eof ) ) ) break;

        if( b_eof ) return VLC_EGENERIC;

        msleep( STREAM_DATA_WAIT );
    }

    while( b )
    {
        i_stop = mdate();

        /* Append the block */
        p_sys->block.i_size += b->i_buffer;
        *p_sys->block.pp_last = b;
        p_sys->block.pp_last = &b->p_next;

        /* Fix p_current */
        if( p_sys->block.p_current == NULL )
            p_sys->block.p_current = b;

        /* Update stat */
        p_sys->stat.i_bytes += b->i_buffer;
        p_sys->stat.i_read_time += i_stop - i_start;
        p_sys->stat.i_read_count++;

        b = b->p_next;
        i_start = mdate();
    }
    return VLC_SUCCESS;
}


/****************************************************************************
 * Method 2:
 ****************************************************************************/
static int AStreamRefillStream( stream_t *s );

static int AStreamReadStream( stream_t *s, void *p_read, unsigned int i_read )
{
    stream_sys_t *p_sys = s->p_sys;
    stream_track_t *tk = &p_sys->stream.tk[p_sys->stream.i_tk];

    uint8_t *p_data = (uint8_t *)p_read;
    unsigned int i_data = 0;

    if( tk->i_start >= tk->i_end ) return 0; /* EOF */

    if( p_read == NULL )
    {
        /* seek within this stream if possible, else use plain old read and discard */
        stream_sys_t *p_sys = s->p_sys;
        access_t     *p_access = p_sys->p_access;

        /* seeking after EOF is not what we want */
        if( !( p_access->info.b_eof ) )
        {
            bool   b_aseek;
            access_Control( p_access, ACCESS_CAN_SEEK, &b_aseek );
            if( b_aseek )
                return AStreamSeekStream( s, p_sys->i_pos + i_read ) ? 0 : i_read;
        }
    }

#ifdef STREAM_DEBUG
    msg_Dbg( s, "AStreamReadStream: %d pos=%"PRId64" tk=%d start=%"PRId64
             " offset=%d end=%"PRId64,
             i_read, p_sys->i_pos, p_sys->stream.i_tk,
             tk->i_start, p_sys->stream.i_offset, tk->i_end );
#endif

    while( i_data < i_read )
    {
        int i_off = (tk->i_start + p_sys->stream.i_offset) %
                    STREAM_CACHE_TRACK_SIZE;
        unsigned int i_current =
            __MAX(0,__MIN( tk->i_end - tk->i_start - p_sys->stream.i_offset,
                   STREAM_CACHE_TRACK_SIZE - i_off ));
        int i_copy = __MIN( i_current, i_read - i_data );

        if( i_copy <= 0 ) break; /* EOF */

        /* Copy data */
        /* msg_Dbg( s, "AStreamReadStream: copy %d", i_copy ); */
        if( p_data )
        {
            memcpy( p_data, &tk->p_buffer[i_off], i_copy );
            p_data += i_copy;
        }
        i_data += i_copy;
        p_sys->stream.i_offset += i_copy;

        /* Update pos now */
        p_sys->i_pos += i_copy;

        /* */
        p_sys->stream.i_used += i_copy;
        if( tk->i_start + p_sys->stream.i_offset >= tk->i_end ||
            p_sys->stream.i_used >= p_sys->stream.i_read_size )
        {
            if( AStreamRefillStream( s ) )
            {
                /* EOF */
                if( tk->i_start >= tk->i_end ) break;
            }
        }
    }

    return i_data;
}

static int AStreamPeekStream( stream_t *s, const uint8_t **pp_peek, unsigned int i_read )
{
    stream_sys_t *p_sys = s->p_sys;
    stream_track_t *tk = &p_sys->stream.tk[p_sys->stream.i_tk];
    int64_t i_off;

    if( tk->i_start >= tk->i_end ) return 0; /* EOF */

#ifdef STREAM_DEBUG
    msg_Dbg( s, "AStreamPeekStream: %d pos=%"PRId64" tk=%d "
             "start=%"PRId64" offset=%d end=%"PRId64,
             i_read, p_sys->i_pos, p_sys->stream.i_tk,
             tk->i_start, p_sys->stream.i_offset, tk->i_end );
#endif

    /* Avoid problem, but that should *never* happen */
    if( i_read > STREAM_CACHE_TRACK_SIZE / 2 )
        i_read = STREAM_CACHE_TRACK_SIZE / 2;

    while( tk->i_end - tk->i_start - p_sys->stream.i_offset < i_read )
    {
        if( p_sys->stream.i_used <= 1 )
        {
            /* Be sure we will read something */
            p_sys->stream.i_used += i_read -
                (tk->i_end - tk->i_start - p_sys->stream.i_offset);
        }
        if( AStreamRefillStream( s ) ) break;
    }

    if( tk->i_end - tk->i_start - p_sys->stream.i_offset < i_read )
        i_read = tk->i_end - tk->i_start - p_sys->stream.i_offset;

    /* Now, direct pointer or a copy ? */
    i_off = (tk->i_start + p_sys->stream.i_offset) % STREAM_CACHE_TRACK_SIZE;
    if( i_off + i_read <= STREAM_CACHE_TRACK_SIZE )
    {
        *pp_peek = &tk->p_buffer[i_off];
        return i_read;
    }

    if( p_sys->i_peek < i_read )
    {
        p_sys->p_peek = realloc( p_sys->p_peek, i_read );
        if( !p_sys->p_peek )
        {
            p_sys->i_peek = 0;
            return 0;
        }
        p_sys->i_peek = i_read;
    }

    memcpy( p_sys->p_peek, &tk->p_buffer[i_off],
            STREAM_CACHE_TRACK_SIZE - i_off );
    memcpy( &p_sys->p_peek[STREAM_CACHE_TRACK_SIZE - i_off],
            &tk->p_buffer[0], i_read - (STREAM_CACHE_TRACK_SIZE - i_off) );

    *pp_peek = p_sys->p_peek;
    return i_read;
}

static int AStreamSeekStream( stream_t *s, int64_t i_pos )
{
    stream_sys_t *p_sys = s->p_sys;
    access_t     *p_access = p_sys->p_access;
    bool   b_aseek;
    bool   b_afastseek;
    int i_maxth;
    int i_new;
    int i;

#ifdef STREAM_DEBUG
    msg_Dbg( s, "AStreamSeekStream: to %"PRId64" pos=%"PRId64
             " tk=%d start=%"PRId64" offset=%d end=%"PRId64,
             i_pos, p_sys->i_pos, p_sys->stream.i_tk,
             p_sys->stream.tk[p_sys->stream.i_tk].i_start,
             p_sys->stream.i_offset,
             p_sys->stream.tk[p_sys->stream.i_tk].i_end );
#endif


    /* Seek in our current track ? */
    if( i_pos >= p_sys->stream.tk[p_sys->stream.i_tk].i_start &&
        i_pos < p_sys->stream.tk[p_sys->stream.i_tk].i_end )
    {
        stream_track_t *tk = &p_sys->stream.tk[p_sys->stream.i_tk];
#ifdef STREAM_DEBUG
        msg_Dbg( s, "AStreamSeekStream: current track" );
#endif
        p_sys->i_pos = i_pos;
        p_sys->stream.i_offset = i_pos - tk->i_start;

        /* If there is not enough data left in the track, refill  */
        /* \todo How to get a correct value for
         *    - refilling threshold
         *    - how much to refill
         */
        if( (tk->i_end - tk->i_start ) - p_sys->stream.i_offset <
                                             p_sys->stream.i_read_size )
        {
            if( p_sys->stream.i_used < STREAM_READ_ATONCE / 2  )
            {
                p_sys->stream.i_used = STREAM_READ_ATONCE / 2 ;
                AStreamRefillStream( s );
            }
        }
        return VLC_SUCCESS;
    }

    access_Control( p_access, ACCESS_CAN_SEEK, &b_aseek );
    if( !b_aseek )
    {
        /* We can't do nothing */
        msg_Dbg( s, "AStreamSeekStream: can't seek" );