[FFmpeg-devel] theora depayloader

[Martin Storsjö]

On Fri, 19 Mar 2010, Josh Allmann wrote:

> Updated patch attached, with fixes that everybody suggested. Comments below:
> 

> +        // fast first pass to calculate total length
> +        for (i = 0, data_len = 0, pkt_len = 0;
> +             i < num_pkts && len > 0;
> +             i++) {
> +            int off = data_len+(i<<1);
> +            pkt_len = AV_RB16(buf+off);

Add some spacing around the operators here, for better readability...

> +            data_len += pkt_len;
> +            len -= pkt_len+2;
> +       }
> +
> +       if (len < 0){
> +          av_log(ctx, AV_LOG_ERROR, 
> +                 "Length overread by %d\n", -len);
> +       }

Here, you could potentially get the case where len reaches exactly zero, 
before i has reached num_pkts, so we'd get no warning even if the packet 
was invalid...

> +       if (av_new_packet(pkt, data_len)){
> +          av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");
> +          return AVERROR_NOMEM;
> +       }
> +       pkt->stream_index = st->index;
> +
> +       // concatenate frames
> +       for (i = 0, write_len = 0;
> +            write_len < data_len;
> +            i++){
> +           pkt_len = AV_RB16(buf);
> +           buf += 2;
> +           memcpy(pkt->data+write_len, buf, pkt_len);
> +           write_len += pkt_len;
> +           buf += pkt_len;
> +       }
> +       assert(write_len == data_len);
> +
> +        return 0;

Indentation off

> +    }else{

Spaces around the braces

> +        assert(fragmented < 4);
> +        if (data->timestamp != *timestamp){
> +          // skip if fragmented timestamp is incorrect;
> +          // a start packet has been lost somewhere
> +          free_fragment_if_needed(data);
> +          av_log(ctx, AV_LOG_ERROR, "RTP timestamps don't match!\n");
> +          return AVERROR_INVALIDDATA;
> +        }
> +
> +        // copy data to fragment buffer
> +        put_buffer(data->fragment, buf, pkt_len);
> +
> +        if (fragmented == 3) {
> +            // end of theora data packet
> +            uint8_t* theora_data;
> +            int frame_size = url_close_dyn_buf(data->fragment, &theora_data);
> +
> +            if (frame_size < 0){
> +              av_log(ctx, AV_LOG_ERROR, "Error occurred when getting fragment buffer.");
> +              return frame_size;
> +            }

Indentation off

// Martin