All options of the -map commands must be separated by white spaces. The FFmpeg -map command is used to map and use each scaled output stream. The filter graph sequence should not end with ' If xvbm_convert filters must be added to the filter graph, they must be preceded by a semi-colon ( ) The entire filter graph sequence must be enclosed in quotes ( ')Įach option of the multiscale_xma filter (outputs, width, height, rate) must be separated by a colon ( :)Ī white space must separate the last multiscale_xma option from the list of output names The filter graph syntax must follow these rules: If the outputs are not to encoded on the device, add xvbm_convert filters to the filter graph to reformat the pixels Set the width, height, and rate settings for each scaler output The filter graph specification should be constructed in the following way:Īdd the multiscale_xma filter to the graph This section describes the FFmpeg syntax to configure the scaler, create ABR ladders and use the corresponding output streams.Īn ABR ladder is created using the FFmpeg -filter_complex '' syntax. Since the output of one scaling stage is passed as an input to the next, visual quality will be negatively affected if frame rate is increased after it has been lowered.

IMPORTANT: The frame rate and resolution of a given output should be smaller or equal than the rate of the previous output. The figure below illustrates a scaling ladder with a 1920x1080 input and 4 outputs with resolutions of 1280x720, 852x480, 640x360, and 416x240, respectively. The scaler passes scaled frames and meta data to the next scaling level (if one is defined) and to the encoder (if one is being used)Įach level of scaling adds a little more latency to the pipelineįor additional details about the specification of the hardware scaler, refer to the Adaptive Bitrate Scaler features section in the introductory chapter of this user guide. Scaled output streams can optionally be encoded to H.264 of HEVC, using the same codec for all streams The scaler supports spatial resolutions from 3840x2160 to 128x128, in multiples of 4 Up to 32 scaled outputs streams are supported per device, up to a maximum total equivalent bandwidth of 4kp60 Up to 32 input streams of raw or encoded video can be scaled down per deviceĮach input stream can be scaled down to a maximum of 8 outputs streams of lower resolution and/or lower frame rate The Xilinx Video SDK supports the following scaling features and capabilities: Using the Multiscale XMA FFmpeg plug-in included in the Xilinx Video SDK, each input channel can be scaled in hardware to multiple lower resolution and/or lower frame rate outputs. Each device on an Alveo U30 card supports multiple input channels (raw or encoded) up to a total equivalent bandwidth of 4kp60. The Alveo U30 card provides hardware-accelerated video decoding, scaling, and encoding. Using FFmpeg for Video Scaling on Alveo U30 ¶ If no value is specified for the -spatial-aq-gain option, the default value is 50. To enable spatial AQ, set the -spatial-aq-gain to 1 and the -spatial-aq-gain to 50 on the FFmpeg command line. The range of this option is from 0 to 100 and indicates the strength of this algorithm as a percentage.

The spatial AQ algorithm can be controlled using the -spatial-aq-gain option. It is recommended to turn this feature off when performing PSNR/VMAF based evaluation. Although spatial AQ improves visual quality, it hurts objective metrics and causes a drop in PSNR and VMAF. This redistribution of bits to visually perceptible regions of the frame brings about visual improvement. Spatial AQ exploits this and provides more bits to the low texture and flat regions at the expense of high texture regions. The human eye is more sensitive to regions which are flat and have low texture than regions which have lots of detail and texture. Spatial AQ adjusts the QP within a frame based on the spatial characteristics. Using FFmpeg for Video Scaling on Alveo U30.Considerations for Decoding and Encoding 4K Streams.Using FFmpeg for Video Encoding and Decoding on Alveo U30.

Ffmpeg convert frame rate and speed