Hi Folks, I am coming back around to trying to refine out ffmpeg parameters for mobile video calls. Our end user device is a 3G video phone mobile. However the telephony server accepts AVI's with PCM audio and H263 video. The PCM audio will be transcoded to AMR via the SIP->TDM gateway and sent I assume as a 3GPP data stream. So our target is: AVI + H263 @ 176x144 @ NO MORE than 50kbit/s + PCM @ 8000Hz Currently we are using parameters like (justifications in brackets) -f avi -b 40k -ac 1 -g 30 (aiming for rougly 1 IFrame every 2 seconds) -r 15 -ps 400 (can't explain this one, but higher or lower values simply don't work very well) -qscale 10 (We use this as our primary quality<->bitrate trade off value) -vcodec h263 -s qcif -acodec pcm_mulaw -ar 8000 This 'works' okay, but it's not great. At the moment we are lucky that our SIP->TDM gateway buffers any bit rate overrun causing slight lag only. Other gateways we have used are not so forgiving. We have played with the bitrate tolerance, but could not get working results. What I would like to achieve is progressiveness in the quality. Best to use an example.... Take an image that is fairly complex and has fairly small text. I believe it should be possible to sequence this into an h263 video stream and while the initial IFrame may not be able to provide much quality, the subsequent B/P? frames should be able to improve upon it. In other words if the image is static in the video can the bandwidth not be used to increase the definition.... sort of similar to a progressive JPEG. Is this possible with H263? Can anyone suggest different parameters to better utilise the 50kbit available for video? Thanks for any advice, Paul?Campbell? -------------------------------------------------------------------- This e-mail is intended solely for the addressee and is strictly confidential; if you are not the addressee please destroy the message and all copies. Any opinion or information contained in this email or its attachments that does not relate to the business of Kainos is personal to the sender and is not given by or endorsed by Kainos. Kainos is the trading name of Kainos Software Limited, registered in Northern Ireland under company number: NI19370, having its registered offices at: Kainos House, 4-6 Upper Crescent, Belfast, BT7 1NT, Northern Ireland. Registered in the UK for VAT under number: 454598802 and registered in Ireland for VAT under number: 9950340E. This email has been scanned for all known viruses by MessageLabs but is not guaranteed to be virus free; further terms and conditions may be found on our website - www.kainos.com