Decoding Dynamic Payloads

asked 2020-08-31 02:36:39 +0000

Eagle gravatar image

updated 2020-08-31 02:46:30 +0000

Dear Sir, I have one observation while breaking Dynamic payloads, that whatever preference I suggest to Wireshark, it accepts that. I mean when I select H.264 as Dynamic Payload preference, RTP changes to H.264, when I changed preference to H.265, then RTP changes to H.265. likewise I changed 02-03 more encodings(G.723.1, H.263P) and RTP got changed accordingly. Overall what I want to ask is that if wireshark take the preference and let the RTP changed accordingly, how would we come to know that which exact encoding has been used in the Dynamic Payload? Anybody might be wrong while giving preference to Wireshark to decode the Dynamic Payload, because he is just guessing the encoding to break the payload. I mean instead of our preference wireshark must take the exact one encoding used in the payload. More over No SDP information in my capture packet, so that I could know the kind of media flowing over SIP/SDP. If I'm wrong plz correct me and suggest correctness. My second question is that I gave preference as H.264 and hence analysed packets and save the payloads as .au and .raw format. Now when I'm playing this file through my VLC player, there is nothing, it's totally blank screen, no sound nothing. Thereafter I go to VLC setting for H.264, input and codecs, demuxers etc., then I played that file, again got nothing. Thereafter I converted that file to .mp4 using file converter software and again I didn't get the desired results. I'm totally collapsed. Not able to understand what to do and how to play the file. File size is 158 MB. WS version 3.2.6. Also I've one doubt that if the actual file is using H.264 encoding and I'm saving the file as .au and .raw file then how could VLC play and show that file as H.264? How to change that .au file to its original encoding form that is H.264. I'm totally confused. Anyone who could answer my questions? Regards.

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This journal article Fast RTP Detection and Codecs Classification in Internet Traffic may help. Wireshark may not be the best tool for your goal. The authors mention their tool RTPinfo but give no link to it.

Chuckc gravatar imageChuckc ( 2020-08-31 03:11:26 +0000 )edit