avformat/rtpenc: adds partial support for the RFC 4175

Reviewed-by: Lynne <dev@lynne.ee>
Signed-off-by: Limin Wang <lance.lmwang@gmail.com>

1 files changed, 116 insertions, 0 deletions

diff --git a/libavformat/rtpenc_rfc4175.c b/libavformat/rtpenc_rfc4175.c
new file mode 100644
index 0000000000..6fa34b64cb
--- /dev/null
+++ b/libavformat/rtpenc_rfc4175.c
@@ -0,0 +1,116 @@
+/*
+ * RTP Packetization of RAW video (RFC4175)
+ * Copyright (c) 2021 Limin Wang
+ *
+ * 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"
+
+void ff_rtp_send_raw_rfc4175(AVFormatContext *s1, const uint8_t *buf, int size)
+{
+    RTPMuxContext *s = s1->priv_data;
+    int width = s1->streams[0]->codecpar->width;
+    int height = s1->streams[0]->codecpar->height;
+    int xinc, yinc, pgroup;
+    int field = 0;
+    int i = 0;
+    int offset = 0;
+
+    s->timestamp = s->cur_timestamp;
+    switch (s1->streams[0]->codecpar->format) {
+        case AV_PIX_FMT_UYVY422:
+            xinc = yinc = 2;
+            pgroup = 4;
+            break;
+        case AV_PIX_FMT_YUV420P:
+            xinc = yinc = 4;
+            pgroup = 6;
+            break;
+        default:
+            return;
+    }
+
+    while (i < height) {
+        int left = s->max_payload_size;
+        uint8_t *dest = s->buf;
+        uint8_t *headers;
+        const int head_size = 6;
+        int next_line;
+        int length, cont, pixels;
+
+        /* Extended Sequence Number */
+        *dest++ = 0;
+        *dest++ = 0;
+        left   -= 2;
+
+        headers = dest;
+        do {
+            pixels = width * xinc - offset;
+            length = (pixels * pgroup) / xinc;
+
+            left -= head_size;
+            if (left >= length) {
+                next_line = 1;
+            } else {
+                pixels = (left / pgroup) * xinc;
+                length = (pixels * pgroup) / xinc;
+                next_line = 0;
+            }
+            left -= length;
+
+            /* Length */
+            *dest++ = (length >> 8) & 0xff;
+            *dest++ = length & 0xff;
+
+            /* Line No */
+            *dest++ = ((i >> 8) & 0x7f) | ((field << 7) & 0x80);
+            *dest++ = i & 0xff;
+            if (next_line) i += yinc;
+
+            cont = (left > (head_size + pgroup) && i < height) ? 0x80 : 0x00;
+            /* Offset and Continuation marker */
+            *dest++ = ((offset >> 8) & 0x7f) | cont;
+            *dest++ = offset & 0xff;
+
+            if (next_line)
+                offset  = 0;
+            else
+                offset += pixels;
+        } while (cont);
+
+        do {
+            int l_line;
+            int l_off;
+            int copy_offset;
+
+            length    = (headers[0] << 8) | headers[1];
+            l_line    = ((headers[2] & 0x7f) << 8) | headers[3];
+            l_off     = ((headers[4] & 0x7f) << 8) | headers[5];
+            cont      = headers[4] & 0x80;
+            headers  += head_size;
+
+            copy_offset = (l_line * width + l_off) * pgroup / xinc;
+            if (copy_offset + length > size)
+                break;
+            memcpy (dest, buf + copy_offset, length);
+            dest += length;
+        } while (cont);
+
+        ff_rtp_send_data (s1, s->buf, s->max_payload_size - left, i >= height);
+    }
+}