avformat/whip: add srtp setup for video rtx

unique ssrc need to use unique srtp context, otherwise the server couldn't decrypted the rtx packet. move the "a=ssrc-group:FID" on top of SSRCs Signed-off-by: Jack Lau <jacklau1222@qq.com>

Author: JackLau1222

libavformat/whip.c

@@ -294,6 +294,7 @@ typedef struct WHIPContext {
  /* The SRTP send context, to encrypt outgoing packets. */
  SRTPContext srtp_audio_send;
  SRTPContext srtp_video_send;
+ SRTPContext srtp_video_rtx_send;
  SRTPContext srtp_rtcp_send;
  /* The SRTP receive context, to decrypt incoming packets. */
  SRTPContext srtp_recv;
@@ -717,11 +718,11 @@ static int generate_sdp_offer(AVFormatContext *s)
  "a=rtcp-fb:%u nack\r\n"
  "a=rtpmap:%u rtx/90000\r\n"
  "a=fmtp:%u apt=%u\r\n"
+ "a=ssrc-group:FID %u %u\r\n"
  "a=ssrc:%u cname:FFmpeg\r\n"
  "a=ssrc:%u msid:FFmpeg video\r\n"
  "a=ssrc:%u cname:FFmpeg\r\n"
- "a=ssrc:%u msid:FFmpeg video\r\n"
- "a=ssrc-group:FID %u %u\r\n",
+ "a=ssrc:%u msid:FFmpeg video\r\n",
  whip->video_payload_type,
  whip->rtx_payload_type,
  whip->ice_ufrag_local,
@@ -738,10 +739,10 @@ static int generate_sdp_offer(AVFormatContext *s)
  whip->rtx_payload_type,
  whip->video_payload_type,
  whip->video_ssrc,
- whip->video_ssrc,
- whip->video_rtx_ssrc,
  whip->video_rtx_ssrc,
  whip->video_ssrc,
+ whip->video_ssrc,
+ whip->video_rtx_ssrc,
  whip->video_rtx_ssrc);
  }
 
@@ -1442,6 +1443,12 @@ static int setup_srtp(AVFormatContext *s)
  goto end;
  }
 
+ ret = ff_srtp_set_crypto(&whip->srtp_video_rtx_send, suite, buf);
+ if (ret < 0) {
+ av_log(whip, AV_LOG_ERROR, "WHIP: Failed to set crypto for video rtx send\n");
+ goto end;
+ }
+
  ret = ff_srtp_set_crypto(&whip->srtp_rtcp_send, suite, buf);
  if (ret < 0) {
  av_log(whip, AV_LOG_ERROR, "Failed to set crypto for rtcp send\n");
@@ -1583,7 +1590,7 @@ static int send_rtx_packet(AVFormatContext *s, const uint8_t * orig_pkt, int ori
  new_size = orig_size + 2;
 
  /* Encrypt by SRTP and send out. */
- cipher_size = ff_srtp_encrypt(&whip->srtp_video_send, whip->buf, new_size, whip->buf, sizeof(whip->buf));
+ cipher_size = ff_srtp_encrypt(&whip->srtp_video_rtx_send, whip->buf, new_size, whip->buf, sizeof(whip->buf));
  if (cipher_size <= 0 || cipher_size < new_size) {
  av_log(whip, AV_LOG_WARNING, "WHIP: Failed to encrypt packet=%dB, cipher=%dB\n", new_size, cipher_size);
  return 0;