[FFmpeg-devel] [PATCH] mp4a-latm rtp output & dynamic payload type from URL

[Luca Abeni]

After having a look at RFC3016, I have another question about
LATM in RTP:

Luca Abeni wrote:
[...]
> Finally, one doubt about the code:
> [...]
> +/* latm muxer */
> +void ff_rtp_send_aac_latm(AVFormatContext *s1, const uint8_t *buff, int 
> size)
> +{
> +    RTPMuxContext *s = s1->priv_data;
> +    int len, max_packet_size;
> +    uint8_t *p = s->buf;
> +    int latmhdrsize;
> +
> +    /* skip ADTS header, if present */
> +    if ((s1->streams[0]->codec->extradata_size) == 0) {
> +        size -= 7;
> +        buff += 7;
> +    }
> +
> +    latmhdrsize = size/0xff + 1;
> +    max_packet_size = s->max_payload_size - latmhdrsize;
> +    s->timestamp = s->cur_timestamp;
> +
> +    while (size > 0) {
> +    len = FFMIN(size, max_packet_size);
> +    memcpy(p + latmhdrsize, buff, len);

According to the RFC (Section 4.1), it seems that the LATM
stream is directly copied in the packet payload, without
any payload-specific header:
"...    The first byte of each audioMuxElement SHALL be
located at the first payload location in an RTP packet..."
(also see Figure 4).

So, what is this "latmhdrsize" about? What am I missing?


			Thanks,
				Luca