If I do set a maxrate, it is observed by the encoder. The resultant video has an overall bitrate of ~100Mb/s. I'm seeing the encoder use as many bits as possible, not as many bits as needed. If maxBitRate is not specified, the encoder will use as many bits as needed to achieve the target quality.īut that's not the behavior I'm observing. If I don't specify a maxrate, the documentation indicates: Per documentation, I can also specify a maxBitRate (maxrate=). (Using cq=1, cq=20, and cq=51 all output a file with the same hash.) HOWEVER, that only outputs the same perfect quality video of extremely large size for any cq value. This should be enough to test various values of cq. I specify a Variable Bit Rate rate control mode (rc=vbr_hq) and a target quality (cq=). To use the h264_nvenc encoder through ffmpeg and with a target quality, I follow the instructions in Nvidia's documentation, last paragraph of the linked anchor. NOW, I am going to stick with QSV 2pass, but am wondering if I am doing something wrong, seeing as 1 or 2 pass result in the same file size regardless and how the NVENC file is much smaller in size at the same bitrate when comparing even single pass runs.I seek to ascertain the end-product quality of various cq ('constant quality') values for the h264_nvenc video encoder.

Using the same input file, I also was surprised to have found that the QSV h.264 encoded file is the exact same size after either a 1 or 2 pass run. Is this smaller NVENC encoded file a simple result of lesser quality, even at the same resulting bitrate ? or am I missing something else ? I found that NVENC is obviously faster on it's highest quality single pass compared to QSV (on my hardware), but the NVENC 8192kbps file is also about 2GB Smaller (8GB vs.

I did however do a direct comparison using NVENC, which in VidCoder is limited to single pass work, benchmarking it against QSV in a single pass with all of the same basic settings set to the highest quality file possible. For the last while I have been trying to find a more efficient way to shrink large 1080p MKV files for media server storage and keep them 8196kbps/AC3, before I make the switch entirely to h.265.Īs I was told on this very forum, if a powerful enough CPU wasn't an option, QSV would give me the best image quality results, so that is out of the way.

H264_nvenc quality