[vlc-devel] acces: AMT Module

Natalie Landsberg nlandsberg at juniper.net
Thu Jul 12 18:33:13 CEST 2018


I am planning to chain the TS demux as I have realized that I think TS cannot demux the 30 bytes that are the encapsulation. Thank you for the pointer in that direction, as I think it should help solve the issue.

Also, I have written the necessary aspects for IPv4 and IGMPv3, as that is what I am focused on for now. IPv6 and MLD are not within scope at the moment.



On 7/12/18, 11:23 AM, "Rémi Denis-Courmont" <remi at remlab.net> wrote:

    Le keskiviikkona 11. heinäkuuta 2018, 16.51.23 EEST Natalie Landsberg a écrit 
    > I am writing an access module for VLC that would allow tunneling between
    > native multicast streams and unicast-only networks.
    AFAIU, AMT logically belongs as some kind of pseudo-tunnel device driver 
    within the IP stack. If you implement in VLC, you will have to duplicate IPv4/
    IPv6, UDP/UDP-Lite and IGMP/MLD protocols support :/
    > I have written a
    > majority of the module but am now having issues with receiving the
    > multicast data. I keep getting multiple ts demux warnings, either “lost
    > synchro” or “discontinuity received 0x6 instead of 0x5 (pid=481)” with the
    > numbers changing of course. It is always one off though, so I am wondering
    > if there may possibly be a simple fix?
    It is quite normal to get that at the beginning. Otherwise, it means either TS 
    packet corruption, loss, or reordering. If the network is susceptible to 
    reordering, then TS cannot be carried directly raw over UDP.
    > Or will I have to change my module to an access/demux?
    You can use an access/demux and then chain the TS demux. But I do not really 
    see how it would solve anything; you would probably have the same issues.
    > My module is primarily based off of the udp module,
    > since the packets received are encapsulated udp packets.
    Rémi Denis-Courmont

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