[Libav-user] RTP H.264 private data

Thomas Volkert silvo at gmx.net
Wed May 6 09:40:20 CEST 2015

Am 06.05.2015 um 07:50 schrieb Camera Man:
> On 05/05/2015 11:43 PM, Info || Non-Lethal Applications wrote:
>> Hi guys,
>> I’m sending an H.264 stream from the Mac to an iOS device using 
>> OpenH264 and RTP and it works great.
>> I was wondering if there’s a chance to add private data to the 
>> packets so I could add some info in order to know the exact delay of 
>> the stream?
>> I thought about adding a timestamp of the source machine to every 
>> packet.
> This information was answered specifically about timing source 
> information, but what about the general question? I'm encoding an 
> .h264 file, and would love to put packets inside that identify my 
> software version, incoming stream IP, ffmpeg version - e.g., once 
> every SPS/PPS comes along.
Based on RTP/RTCP encapsulation you could use RTCP source descriptions 
(RTCP type 202) and encode whatever you like inside the transferred 
identifier (a simple string).

> Is there a simple way to do that with ffmpeg? What are the best google 
> keywords to figure this out if not?

Sender side:
AVDictionary        *options = NULL;
string                     streamName = "myStream#myApp 
av_dict_set(&options, "cname", streamName.c_str(), 0)
avformat_write_header(rtpFormatContext, &options)

Check with wireshark und you will see the string inside a RTCP packet.

Best regards,

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