Re: [rtcweb] H261/MPEG-1 video quality (was: I'd love it if patents evaporated)
Adam Roach <adam@nostrum.com> Thu, 14 November 2013 23:16 UTC
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Date: Thu, 14 Nov 2013 17:16:52 -0600
From: Adam Roach <adam@nostrum.com>
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Subject: Re: [rtcweb] H261/MPEG-1 video quality (was: I'd love it if patents evaporated)
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I sent a reply to this earlier, but just now realized that it went only to Justin, not to the list. On 11/14/13 13:59, Justin Uberti wrote: > Thanks, this is interesting. Is the ffmpeg 261 encoder limited to > CIF/QCIF, or can you specify arbitrary sizes? It looks like the ffmpeg mpeg-1 coder works for arbitrary sizes. I'm not sure what the difference between mpeg-1 and H.261 are, though, so we could be talking apples and oranges (or at least apples and pears) here. I'll note that mpeg-1 came out in 1991, which is a good 22 years in the past. I'm not drawing IPR conclusions for you, but invite you to ponder the implications yourself. Following Maik's lead with the mpeg-1 js decoder, I put this together: https://dl.dropboxusercontent.com/u/53717247/mpg/maven.html ...with this commandline: ffmpeg -i maven.mp4 -f mpeg1video -flags qprd -mbd rd -cmp rd -subcmp rd -mbcmp rd -precmp rd -trellis 2 -g 100 -vb 256k maven.mpg I don't really understand most of those options (I just cribbed them from Maik's example) or whether any of them would introduce more latency than is reasonable for a real-time conversation, but I will observe: 1. The encoder claims that it was performing on the order of 90 - 100 fps on my (admittedly modern) system; 2. The resolution is 640x360 (somewhat larger than DCIF); 3. The video is not, to my eye, unusable (draw your own conclusions, as it's clearly not as nice as modern codecs); 4. At 74 seconds and 4.7 MBytes (i.e., 37.6 Mbits), this encoding works out to 508 kbits/second total. Source video here, and NASA is acknowledged as the source of the material contained therein: http://www.youtube.com/watch?v=ijAO0FFExx0 /a
- Re: [rtcweb] H261/MPEG-1 video quality (was: I'd … Leon Geyser
- [rtcweb] H261/MPEG-1 video quality (was: I'd love… Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality (was: I'd … Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality Gili
- Re: [rtcweb] H261/MPEG-1 video quality Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality (was: I'd … Justin Uberti
- Re: [rtcweb] H261/MPEG-1 video quality Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality Gili
- Re: [rtcweb] H261/MPEG-1 video quality (was: I'd … Adam Roach
- Re: [rtcweb] H261/MPEG-1 video quality Adam Roach
- Re: [rtcweb] H261/MPEG-1 video quality Stephan Wenger
- Re: [rtcweb] H261/MPEG-1 video quality Leon Geyser
- Re: [rtcweb] H261/MPEG-1 video quality Monty Montgomery
- Re: [rtcweb] H261/MPEG-1 video quality Leon Geyser
- Re: [rtcweb] H261/MPEG-1 video quality Magnus Westerlund
- Re: [rtcweb] H261/MPEG-1 video quality Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality cowwoc
- Re: [rtcweb] H261/MPEG-1 video quality cowwoc
- Re: [rtcweb] H261/MPEG-1 video quality (was: I'd … cowwoc
- Re: [rtcweb] H261/MPEG-1 video quality Harald Alvestrand
- Re: [rtcweb] H261/MPEG-1 video quality Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality cowwoc
- Re: [rtcweb] H261/MPEG-1 video quality (was: I'd … Justin Uberti
- Re: [rtcweb] H261/MPEG-1 video quality Adam Roach
- Re: [rtcweb] H261/MPEG-1 video quality (was: I'd … Justin Uberti
- Re: [rtcweb] H261/MPEG-1 video quality Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality Stephan Wenger
- Re: [rtcweb] H261/MPEG-1 video quality Gunnar Hellstrom
- Re: [rtcweb] H261/MPEG-1 video quality Randell Jesup
- Re: [rtcweb] H261/MPEG-1 video quality Adam Roach
- Re: [rtcweb] H261/MPEG-1 video quality Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality Maik Merten
- Re: [rtcweb] H261/MPEG-1 video quality Stephan Wenger
- Re: [rtcweb] H261/MPEG-1 video quality Toerless Eckert
- Re: [rtcweb] H261/MPEG-1 video quality Toerless Eckert
- Re: [rtcweb] H261/MPEG-1 video quality Maik Merten
- [rtcweb] Trellis IPR status? (Re: H261/MPEG-1 vid… Harald Alvestrand
- Re: [rtcweb] Trellis IPR status? (Re: H261/MPEG-1… Maik Merten
- Re: [rtcweb] Trellis IPR status? (Re: H261/MPEG-1… Harald Alvestrand
- Re: [rtcweb] Trellis IPR status? (Re: H261/MPEG-1… Maik Merten