[Mp4-tech] fast forward & backward in mpeg-4

[Gopalakrishnan Srinivasan]

Hi Daljit,
           There is a case where only first picture will be I frames and following will be P frames. During this case what we need to do.
            Also number of P frames between two I frames is not constant. It will vary and this case what we need to do. Also as you said it can be max 132 pictures between two I frames and if I need to fast-forward at x30, what we need to do.
Thanks & Regards,
SGK
Daljit <daljit.dhillon patni.com> wrote:
Hi!
You can implement fast forward /rewind functionality by decoding only I frames in the stream in required direction.
You may even choose to skip fix number of these I frames before decoding. i.e. you may choose to decode every fifth I frame in the stream.
For MPEG-4 there can be max 132 inter-coded macroblocks at same location from consecutive frames  between two intra-coded macroblocks in the sequence.
To keep things simple, avoid more than 132 P frames inbetween two I frames.
Regards
-Daljit
-----Original Message-----
From: mp4-tech-bounces lists.mpegif.org [mailto:mp4-tech-bounces lists.mpegif.org]On Behalf Of Gopalakrishnan Srinivasan
Sent: Wednesday, February 02, 2024 6:43 PM
To: mp4-tech lists.mpegif.org
Subject: [Mp4-tech] fast forward & backward in mpeg-4
Hello Experts,
                     I am looking into implementation of fast forward and fast backward in MPEG-4 simple profile & simple level video decoder. But I dont find any information how can we do this. Can anybody help me how can we do this.
                    Also in MPEG-4 video whether there is any maximum limit to place number of "P" frames inbetween two "I" frames.    
Thanks & Regards,
SGK
---------------------------------
Do you Yahoo!?
The all-new My Yahoo! - What will yours do?
http://www.patni.com
World-Wide Partnerships. World-Class Solutions. 
_____________________________________________________________________ 
This e-mail message may contain proprietary, confidential or legally privileged information for the sole use of the person or entity to whom this message was originally addressed. Any review, e-transmission dissemination or other use of or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you have received this e-mail in error kindly delete this e-mail from your records. If it appears that this mail has been forwarded to you without proper authority, please notify us immediately at netadmin patni.com and delete this mail. 
_____________________________________________________________________ _______________________________________________
NOTE: Please use clear subject lines for your posts. Include [audio, [video], [systems], [general] or another apppropriate identifier to indicate the type of question you have.
Note: Conduct on the mailing list is subject to the Antitrust guidelines found at http://www.mpegif.org/public/documents/vault/mp-out-30042-Antitrust.php
---------------------------------
Do you Yahoo!?
 Yahoo! Search presents - Jib Jab's 'Second Term'
-------------- next part --------------
An HTML attachment was scrubbed...
URL: /pipermail/mp4-tech/attachments/20050203/3eda9611/attachment.html