On Mon, Jun 01, 2015 at 04:43:12PM +0200, Christoph Gerstbauer wrote: > Hello > > I am testing the standard "conformness" of ffmpegs IMX50 (Mpeg2 > I-frame, MXF) encoder. > > I mentioned via ffprobe or via encoding that ffmpeg does encode a > NTSC framesize of: "208542". > But the SMPTE Standard 356M-2001 specifies this vlaue with "208541". > For PAL there is no problem, both framesizes are "250000". > > So at the encoding params I have to set the following: > > -bufsize 2000000 (set ratecontrol buffer size (in bits)) > SMPTE for PAL: max coded frame size = 250,000 BYTES = 2000000 bits > SMPTE for NTSC: max codec frame size = 208,541 BYTES = 1668328 bits > -rc_init_occupancy 2000000 (number of bits which should be loaded > into the rc buffer before decoding starts) > SMPTE for PAL: max coded frame size = 250,000 BYTES = 2000000 bits > SMPTE for NTSC: max codec frame size = 208,541 BYTES = 1668328 bits > > But at the NTSC encoding I get get there errors: > > C:\Users\gersti>ffmpegnew -i "C:\Users\gersti\D-10_NTSC.mxf" -map > 0:v -map 0:a -c:v mpeg2video -r 30000/1001 -pix_fmt yuv422p -aspect > 4:3 -minr > ate 50000k -maxrate 50000k -b:v 50000k -g 1 -flags
yes, this happens because 50mbit/sec is not correct a max framesize of 208541 results in a bit rate of max 49.999840 mbit/sec, IIUC thats what the spec means by 50mbit/sec check yourself: 208541 * 8 * 30000/1001 [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB I know you won't believe me, but the highest form of Human Excellence is to question oneself and others. -- Socrates
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