Encoding files with Open-GOPs is supposed to produce better quality than closed GOPs because B and P frames can reference frames located outside the GOP. However, files produced for ABR streaming should have closed GOPs. This paper explores the defaults for x264 and x265, the quality difference between closed and open GOPs, and the RADL…
On September 11, 2019, Streaming Media Magazine published an article entitled Hardware-Based Transcoding Solutions Roundup: Testing Performance, that compared various H.264 and HEVC encoders using objective and subjective testing. The HEVC encoders tested included Intel’s SVT (Scalable Video Technology)-HEVC, a software-based codec; NGCodec’s FPGA-based HEVC encoder (now owned by Xilinx) and x265 using the medium…
All codecs and encoding tools have a configuration option that controls the quality/encoding time tradeoff. With x264 (and x265) the preset controls that tradeoff. When choosing a preset you should consider 3 criteria: Overall quality – the overall quality produced by that preset Low frame quality – the quality of the lowest frame produced by…
Many producers distribute the same encoding ladder to all viewers. However, sending a 1080p stream to smartphone viewers may be a waste of bandwidth as both SSIMPLUS and VMAF scores reveal that lower resolution, lower-bandwidth videos deliver similar quality at a lower cost. This tutorial, from my course Computing and Using Video Quality Metrics, shows…
On August 12, 2019, I reported in Streaming Media Magazine that the hugely unpopular MPEG LA DASH Pool might be shutting down. I shared what was purported to be a draft letter from MPEG LA President Larry Horn to pool members which stated the following: “Regrettably, with more than one year’s experience marketing the DASH…
Announcing a new online course entitled, Computing and Using Video Quality Metrics: A Course for Encoding Professionals. The course contains over four hours of video instruction and costs $99.95. The course teaches you how to choose, compute, and interpret video quality metrics like VMAF, SSIMPLUS, PSNR, and SSIM. Here are some of the key items you…
One of the first operations I learned in FFmpeg was how to scale subsampled video files back to the source resolution to compute PSNR in the Moscow State University (MSU) Video Quality Measurement Tool (VQMT). Thankfully, for those not familiar with FFmpeg, as of VQMT version 11.1, this operation is no longer necessary. Yup, VQMT…
So, I received an email from an acquaintance that read, “I was curious if there is actually any benefit to a “threads=” type custom command in x264. Specifically many streamers are buying 8 core/16 thread CPUs to encode as a standalone client capturing information from a video capture device.” I had an article on FFmpeg…
This article has been superseded by this article entitled, An FFmpeg Script to Render and Package a Complete HLS Presentation. So there I was, teaching a class at Streaming Media East entitled How To Build A Free Encoder/Packager With Watch Folder Operation Using Open Source Tools (handout and video available here). An attendee asked about…
This article discusses the evolution of the encoding ladder from the fixed ladder presented by Apple in Tech Note TN2224 to context-aware-encoding, which creates a ladder that not only considers the encoding complexity of the content, but also the producer’s QoE and QoS metrics. The encoding ladder embodies the most significant encoding decisions made by…
