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Simple H264 Internet encoding with FFmpeg

Most common use case is to normalize audio level and reduce video bitrate before placing video on internet. We use H264 codec, High profile 4.2 and bitrate 4500k for FullHD footage. This profile is supported by iPhone 6 and iPad mini see here. Because we are using command line manually and want just quick conversion we will use single pass encoding. ffmpeg -hide_banner -i <input> -af loudnorm=I=-14:TP=-1:print_format=summary:offset=1.4,aresample=48k -vcodec libx264 -b:v 4600k -acodec libfdk_aac -profile:v High -preset slow -g 100 -level:v 4. [Read More]

50 Intermediate Codecs compared

One of most often linked pages in video editing tutorials is Compare 50 Intermediate Codecs. This page compares bitrates of several industry standard intermediate codecs: DPX, Cineform, DNxHD, DNxHR, ProRes.

Intermediate codecs are used during editing video. Their advantage over highly compressed codecs like VP9 or H265 is very fast decompression at cost of much larger files.

Distributed randomness

Organization called League of Entropy is working on providing decentralized randomness beacon. Software implentation is called drand. League of entropy runs public pool where anybody can get high quality randomness. Entropy is collected from high quality randomness sources, such as lava lamps. Pool endpoints are listed here. Here you can see pool metadata. Randomness is 32 bytes long and its changing every 30 seconds. You can get not only current randomness but also all past numbers. [Read More]

IEEE-754 storing of floating point numbers

How are floating point numbers stored in computer? To understand how IEEE-754 Floating Point numbers works internally visit IEEE-754 Floating Point Converter.

It can convert floating point numbers from or to their internal binary representation. 32-bit floating point numbers are stored 1 sign bit, 7 bit exponent, 24 bit mantissa.

Video file size calculator

When you are working with professional video formats its always good to know estimated file sizes. Files are pretty big - up to 2 GB/minute for FullHD 1080p 30fps video.

There is pretty nice Omni Video size calculator where you can compute size of most common professional video formats such as AVID, Cineform, DNxHD, ProRes, REDCODE, DVCPROHD. Note that very common DNxHR codec is not included.

Opensource Internet speed test

There are many tests checking your internet speed. Usually these tests are will harvest data from you as much as possible, sell you ads, track you and sell your data to advertising companies.

Libre Speed - Open Source Test

This test is different. Its open source with code available on GitHub. No tracking, no ads. Just a simple test.

https://librespeed.org/

Exporting audio to 32-bit WAV with FFmpeg

32-bit WAV is most flexible uncompressed audio format. Its pretty widely supported with few exceptions - for example Apple Logic, mobile Cubasis and some others won’t open it. Its good format if you need to pass audio from one program to another or for mastering. Main advantage of this format is higher resolution then 24-bit PCM audio and it won’t clip audio, so you do not have to care about overshooting magical 0 dBFS line with True Peaks. [Read More]

Encoding video with FFmpeg for internet distribution

We are going to encode video file for internet distribution using FFmpeg. Lets take a look at out source file: $ ffprobe -hide_banner video.mp4 Input #0, mp4: Duration: 00:05:12.09, start: 0.000000, bitrate: 5521 kb/s Stream #0:0: Video: h264 (Main) avc1, yuv420p, 1920x1080, 25 fps Stream #0:1: Audio: aac (LC) mp4a, 44100 Hz, stereo, 262 kb/s Input is FullHD video, H264, 25 frames per second, 5.5Mbit with 256kbit AAC-LC audio. We want to distribute patent free 720p video. [Read More]