yading@11: /*
yading@11:  * RTP packetization for Xiph audio and video
yading@11:  * Copyright (c) 2010 Josh Allmann
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "libavutil/avassert.h"
yading@11: #include "avformat.h"
yading@11: #include "rtpenc.h"
yading@11: 
yading@11: /**
yading@11:  * Packetize Xiph frames into RTP according to
yading@11:  * RFC 5215 (Vorbis) and the Theora RFC draft.
yading@11:  * (http://svn.xiph.org/trunk/theora/doc/draft-ietf-avt-rtp-theora-00.txt)
yading@11:  */
yading@11: void ff_rtp_send_xiph(AVFormatContext *s1, const uint8_t *buff, int size)
yading@11: {
yading@11:     RTPMuxContext *s = s1->priv_data;
yading@11:     int max_pkt_size, xdt, frag;
yading@11:     uint8_t *q;
yading@11: 
yading@11:     max_pkt_size = s->max_payload_size;
yading@11: 
yading@11:     // set xiph data type
yading@11:     switch (*buff) {
yading@11:     case 0x01:   // vorbis id
yading@11:     case 0x05:   // vorbis setup
yading@11:     case 0x80:   // theora header
yading@11:     case 0x82:   // theora tables
yading@11:         xdt = 1; // packed config payload
yading@11:         break;
yading@11:     case 0x03:   // vorbis comments
yading@11:     case 0x81:   // theora comments
yading@11:         xdt = 2; // comment payload
yading@11:         break;
yading@11:     default:
yading@11:         xdt = 0; // raw data payload
yading@11:         break;
yading@11:     }
yading@11: 
yading@11:     // Set ident.
yading@11:     // Probably need a non-fixed way of generating
yading@11:     // this, but it has to be done in SDP and passed in from there.
yading@11:     q = s->buf;
yading@11:     *q++ = (RTP_XIPH_IDENT >> 16) & 0xff;
yading@11:     *q++ = (RTP_XIPH_IDENT >>  8) & 0xff;
yading@11:     *q++ = (RTP_XIPH_IDENT      ) & 0xff;
yading@11: 
yading@11:     // set fragment
yading@11:     // 0 - whole frame (possibly multiple frames)
yading@11:     // 1 - first fragment
yading@11:     // 2 - fragment continuation
yading@11:     // 3 - last fragmement
yading@11:     frag = size <= max_pkt_size ? 0 : 1;
yading@11: 
yading@11:     if (!frag && !xdt) { // do we have a whole frame of raw data?
yading@11:         uint8_t *end_ptr = s->buf + 6 + max_pkt_size; // what we're allowed to write
yading@11:         uint8_t *ptr     = s->buf_ptr + 2 + size; // what we're going to write
yading@11:         int remaining    = end_ptr - ptr;
yading@11: 
yading@11:         av_assert1(s->num_frames <= s->max_frames_per_packet);
yading@11:         if ((s->num_frames > 0 && remaining < 0) ||
yading@11:             s->num_frames == s->max_frames_per_packet) {
yading@11:             // send previous packets now; no room for new data
yading@11:             ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);
yading@11:             s->num_frames = 0;
yading@11:         }
yading@11: 
yading@11:         // buffer current frame to send later
yading@11:         if (0 == s->num_frames) s->timestamp = s->cur_timestamp;
yading@11:         s->num_frames++;
yading@11: 
yading@11:         // Set packet header. Normally, this is OR'd with frag and xdt,
yading@11:         // but those are zero, so omitted here
yading@11:         *q++ = s->num_frames;
yading@11: 
yading@11:         if (s->num_frames > 1) q = s->buf_ptr; // jump ahead if needed
yading@11:         *q++ = (size >> 8) & 0xff;
yading@11:         *q++ = size & 0xff;
yading@11:         memcpy(q, buff, size);
yading@11:         q += size;
yading@11:         s->buf_ptr = q;
yading@11: 
yading@11:         return;
yading@11:     } else if (s->num_frames) {
yading@11:         // immediately send buffered frames if buffer is not raw data,
yading@11:         // or if current frame is fragmented.
yading@11:         ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);
yading@11:     }
yading@11: 
yading@11:     s->timestamp = s->cur_timestamp;
yading@11:     s->num_frames = 0;
yading@11:     s->buf_ptr = q;
yading@11:     while (size > 0) {
yading@11:         int len = (!frag || frag == 3) ? size : max_pkt_size;
yading@11:         q = s->buf_ptr;
yading@11: 
yading@11:         // set packet headers
yading@11:         *q++ = (frag << 6) | (xdt << 4); // num_frames = 0
yading@11:         *q++ = (len >> 8) & 0xff;
yading@11:         *q++ = len & 0xff;
yading@11:         // set packet body
yading@11:         memcpy(q, buff, len);
yading@11:         q += len;
yading@11:         buff += len;
yading@11:         size -= len;
yading@11: 
yading@11:         ff_rtp_send_data(s1, s->buf, q - s->buf, 0);
yading@11: 
yading@11:         frag = size <= max_pkt_size ? 3 : 2;
yading@11:     }
yading@11: }