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I am trying to check the packets coming from a twitch stream. So, I am using ffprobe to probe on it using the m3u8 playlist link for the video.

the source url for the twitch stream

I notice that the video packets I recieve are bigger in size than MTU(quite bigger for I frames or P frames).

packets sizes

Also, one frame is mapped with one packet. I tested it on multiple APs across pubs and starbucks. I always get one packet per frame. How come ?

I think that the packets are coalesced and hence I see the bigger packets. But I am confused, since I get big packets even on an ethernet connection.

''' ffprobe -v error -select_streams v -show_packets -show_frames '''

taurenfranklin
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1 Answers1

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The term “packet” in ffprobe is not at all related to the term “packet” in TCP. Whether one “packet” is one frame depends on the container and protocol used.

szatmary
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  • Thanks for thr reply ! I went back to ffprobe website to check what exactly -show_packets give information for.It says - **Show information about each packet contained in the input multimedia stream.** I didn't quite understand it. Can you please help me in understanding what exactly am I receiving then if not tcp packets. – taurenfranklin Apr 02 '19 at 14:39
  • It depends on the protocol. For example what would a “packet” be when reading from disk? FFmpeg supports dozens of protocols, everyone will have its own definition. In the case of transport streams, I think it’s a PES packet. Which is (more or less) one video frame. Audio, and data frames depend on the codec. – szatmary Apr 02 '19 at 15:09
  • Packet here refers to chunked data as emitted by the demuxer, with packet boundaries determined by whatever indication is present in the file format. These packets are not essentially related to network transport. – Gyan Apr 02 '19 at 16:13