I am new to authoring BD discs for playback in set top boxes, but I have lots of experience authoring DVDs. Thus, I am very familiar with the need to watch the bit rate carefully to stay within compliance but maxing it out all the same. As a result, I prefer CBR over VBR and just keep to within an hour of video. However, I am finding it a little hard to determine what acceptable bitrate to encode for BR. For example, the x264 guide is strangely silent on the issue:
Wiki says "BD Video movies have a maximum data transfer rate of 54 Mbit/s, a maximum AV bitrate of 48 Mbit/s (for both audio and video data), and a maximum video bit rate of 40 Mbit/s." Link
So, should I just set the x264 example to --bitrate 40000? Keeping in mind, that I am trying to max the quality, so go as high as possible. Also, I am not trying to encode some bit starved stream. The video is shot using an intermediate codec. What do you gurus use? TIA
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High 20's - mid 30's should be ok and don't use CBR.
So for mid-30s would --bitrate 35000 be acceptable? And no CBR? How come? Those two pass --preset veryslow are gonna take forever!
that --bitrate xxxxx example is used for 2pass encoding, which is VBR not CBR
do not encode one pass and using --bitrate xxxxx, it is not optimal
you can kind of simulate CBR mode, you'd have to use CRF and very low quatizer like 10 or so and limit buffers to value you want your stream to be, like --vbv-maxrate 30000 --vbv-bufsize 30000 and even that would not guarantee steady 30.000 stream, peaks might be a bit higher (depends on type of video) and very simple scenes would not give that bitrate anyway
simulating of that CBR stream is kind of not a good idea for Blu-Ray, it might be usable and engineered encoding web stream where you need to limit a stream, but for Blu-Ray use 2pass VBR or CRF, I'd use those --vbv-maxrate 40000 --vbv-bufsize 30000 as mentioned on that web siteas a limit, but beware some authoring software might not like it, find out what buffers need to be set if feeding it to Adobe Encore or DVD Architect etc. For tsMuxeR I guess it does not matter, I would not go over 40.000 in any way. So just to be sure I'd set those buffers 35000 as top numbers.
so for you something like --settings of yours here plus --crf 18 --vbv-maxrate 35000 --vbv-bufsize 30000
seems a good idea, or even a bit lower crf kind of be more aproximate to CBR, like CRF 16 etc.
Last edited by _Al_; 14th Jun 2015 at 18:36.
Thanks so much for the insight. I clearly have a lot to learn yet about blu-ray but you guys have helped a lot.