rtpenc: Allow requesting H264 RTP packetization mode 0

This requires all NAL units to fit within single RTP packets. It
doesn't change the actual packetization for packets that fit, but
errors out and gives a helpful hint if the NAL units would have to
be split, and signals the right packetization mode in the SDP.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/rtpenc.h

@@ -66,12 +66,14 @@ typedef struct RTPMuxContext RTPMuxContext;
 #define FF_RTP_FLAG_MP4A_LATM 1
 #define FF_RTP_FLAG_RFC2190   2
 #define FF_RTP_FLAG_SKIP_RTCP 4
+#define FF_RTP_FLAG_H264_MODE0 8
 
 #define FF_RTP_FLAG_OPTS(ctx, fieldname) \
     { "rtpflags", "RTP muxer flags", offsetof(ctx, fieldname), AV_OPT_TYPE_FLAGS, {.dbl = 0}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "rtpflags" }, \
     { "latm", "Use MP4A-LATM packetization instead of MPEG4-GENERIC for AAC", 0, AV_OPT_TYPE_CONST, {.dbl = FF_RTP_FLAG_MP4A_LATM}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "rtpflags" }, \
     { "rfc2190", "Use RFC 2190 packetization instead of RFC 4629 for H.263", 0, AV_OPT_TYPE_CONST, {.dbl = FF_RTP_FLAG_RFC2190}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "rtpflags" }, \
     { "skip_rtcp", "Don't send RTCP sender reports", 0, AV_OPT_TYPE_CONST, {.dbl = FF_RTP_FLAG_SKIP_RTCP}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "rtpflags" }, \
+    { "h264_mode0", "Use mode 0 for H264 in RTP", 0, AV_OPT_TYPE_CONST, {.dbl = FF_RTP_FLAG_H264_MODE0}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "rtpflags" }, \
 
 void ff_rtp_send_data(AVFormatContext *s1, const uint8_t *buf1, int len, int m);
 

libavformat/rtpenc_h264.c

@@ -55,6 +55,12 @@ static void nal_send(AVFormatContext *s1, const uint8_t *buf, int size, int last
         uint8_t type = buf[0] & 0x1F;
         uint8_t nri = buf[0] & 0x60;
 
+        if (s->flags & FF_RTP_FLAG_H264_MODE0) {
+            av_log(s1, AV_LOG_ERROR,
+                   "NAL size %d > %d, try -slice-max-size %d\n", size,
+                   s->max_payload_size, s->max_payload_size);
+            return;
+        }
         av_log(s1, AV_LOG_DEBUG, "NAL size %d > %d\n", size, s->max_payload_size);
         s->buf[0] = 28;        /* FU Indicator; Type = 28 ---> FU-A */
         s->buf[0] |= nri;

libavformat/sdp.c

@@ -388,15 +388,20 @@ static char *sdp_write_media_attributes(char *buff, int size, AVCodecContext *c,
     char *config = NULL;
 
     switch (c->codec_id) {
-        case CODEC_ID_H264:
+        case CODEC_ID_H264: {
+            int mode = 1;
+            if (fmt && fmt->oformat->priv_class &&
+                av_opt_flag_is_set(fmt->priv_data, "rtpflags", "h264_mode0"))
+                mode = 0;
             if (c->extradata_size) {
                 config = extradata2psets(c);
             }
             av_strlcatf(buff, size, "a=rtpmap:%d H264/90000\r\n"
-                                    "a=fmtp:%d packetization-mode=1%s\r\n",
+                                    "a=fmtp:%d packetization-mode=%d%s\r\n",
                                      payload_type,
-                                     payload_type, config ? config : "");
+                                     payload_type, mode, config ? config : "");
             break;
+        }
         case CODEC_ID_H263:
         case CODEC_ID_H263P:
             /* a=framesize is required by 3GPP TS 26.234 (PSS). It

libavformat/version.h

@@ -31,7 +31,7 @@
 
 #define LIBAVFORMAT_VERSION_MAJOR 54
 #define LIBAVFORMAT_VERSION_MINOR  4
-#define LIBAVFORMAT_VERSION_MICRO  0
+#define LIBAVFORMAT_VERSION_MICRO  1
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \