Re: Fw: [osflash] H.264 NALU in FLV file
Kundan Singh
Hi Franck,
I have successfully played packets with NAL unit types 0x01 and 0x05
in Flash Player. Also for live video from camera in Flash Player 11 I
see these NAL unit types 0x05, 0x01, 0x06 (SEI) and 0x09 (access
delimiter).
The NAL unit type of 0x1b (= 27) is for aggregation as per RTP spec for H.264.
There are two ways for large H.264 NAL units to be sent on network.
First is to use multi-slice per frame, and send one slice as one NAL
unit. This is what can be done by x264 (and other SIP phones) I
believe. Second method is to use RTP packetization mode of 1 and then
new NAL unit types such as 0x1b and 0x1c (actually 24-29) can be used
for aggregation and fragmentation. In particular NAL unit type 28-29
can be used to split the large NAL unit in to smaller fragments and
send each fragment as a single NAL unit. And 24-27 can be used to
aggregate smaller packets into a larger single NAL unit.
In my earlier test, I was not able to use NAL unit type 24 correctly
to combine multiple multi-slice NALUs of single frame to play in Flash
Player. Since you mentioned NAL unit type 27 (=0x1b), I should give
that a try, or perhaps revisit my method of using NAL unit type 24
again. Both 24 and 27 are for aggregation. I should use these to
combine multiple slice NALUs of a single frame before sending to Flash
Player in my siprtmp.
Thanks for the find.
On Sat, Oct 15, 2011 at 9:14 PM, Radsl <ad...@radsl.net> wrote:
> Hi Kundan,
>
> I receveid an email from osflash maling list
> that talk about NALU and youtube.
> it seems that it's an effect wanted by adobe to avoid
> any rip or dump with open source x264 or simply
> use an unusual H264 format to spread trouble...
>
> what do you think ?
>
> Thanks
>
> Franck
>
> ----- Original Message ----- From: "Fujian Li" <fuji...@yahoo.com>
> To: <osf...@osflash.org>
> Sent: Sunday, October 16, 2011 12:02 AM
> Subject: [osflash] H.264 NALU in FLV file
>
>
>> I used Wireshark to capture packets during playing video clips from
>> www.youtube.com. I found all the NALUs have the NAL unit type octet value of
>> 0x41 (F: 0b; NRI: 10b; NAL Unit Type: 00001b). I expected to see some NAL
>> uints with type value of 0x01, or 0x65, etc. But never found. Why?
>>
>> _______________________________________________
>> osflash mailing list
>> osf...@osflash.org
>> http://osflash.org/mailman/listinfo/osflash_osflash.org
>
>
--
Kundan Singh kund...@gmail.com http://kundansingh.com