Add support for AMR audio in the RTP muxer

patch by Martin Storsjö (martin AT martin DOT st)

Originally committed as revision 18375 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 66 insertions, 0 deletions

diff --git a/libavformat/rtp_amr.c b/libavformat/rtp_amr.c
new file mode 100644
index 0000000000..367789fccd
--- /dev/null
+++ b/libavformat/rtp_amr.c
@@ -0,0 +1,66 @@
+/*
+ * RTP packetization for AMR audio
+ * Copyright (c) 2007 Luca Abeni
+ * Copyright (c) 2009 Martin Storsjo
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avformat.h"
+#include "rtpenc.h"
+
+/**
+ * Packetize AMR frames into RTP packets according to RFC 3267,
+ * in octet-aligned mode.
+ */
+void ff_rtp_send_amr(AVFormatContext *s1, const uint8_t *buff, int size)
+{
+    RTPMuxContext *s          = s1->priv_data;
+    int max_header_toc_size   = 1 + s->max_frames_per_packet;
+    uint8_t *p;
+    int len;
+
+    /* Test if the packet must be sent. */
+    len = s->buf_ptr - s->buf;
+    if (s->num_frames == s->max_frames_per_packet || (len && len + size - 1 > s->max_payload_size)) {
+        int header_size = s->num_frames + 1;
+        p = s->buf + max_header_toc_size - header_size;
+        if (p != s->buf)
+            memmove(p, s->buf, header_size);
+
+        ff_rtp_send_data(s1, p, s->buf_ptr - p, 1);
+
+        s->num_frames = 0;
+    }
+
+    if (!s->num_frames) {
+        s->buf[0]    = 0xf0;
+        s->buf_ptr   = s->buf + max_header_toc_size;
+        s->timestamp = s->cur_timestamp;
+    } else {
+        /* Mark the previous TOC entry as having more entries following. */
+        s->buf[1 + s->num_frames - 1] |= 0x80;
+    }
+
+    /* Copy the frame type and quality bits. */
+    s->buf[1 + s->num_frames++] = buff[0] & 0x7C;
+    buff++;
+    size--;
+    memcpy(s->buf_ptr, buff, size);
+    s->buf_ptr += size;
+}
+