Media tools
Sume media tools by API: trim, filter, captions, frames, inspect, speech-to-text, upscaling, background removal, transitions, and Timeline assembly.
Start with Video editing API limits: Sume media tool caps in one table
How to cut a video in half (or into equal parts)
To cut a video in half, split it at its length ÷ 2 into two files. For N equal parts, part i starts at i × length ÷ N. Steps, precision, and limits.
How to split a video by file size without re-encoding
Split a video by file size: scale its length by your limit ÷ its size, cut parts that long without re-encoding, then check each part's size.
How to insert a video into another video
To insert a video into another video, split the main video at the insert point and play it, the new clip, then the rest, all in one render.
How to shorten a video: trim, cut, or remove pauses
Shorten a video by cutting time: trim the start or end, remove sections from the middle, or cut the pauses. Which to pick, how, and the limits.
Types of cuts in video editing: hard, jump, J, L, and more
The main types of cuts in video editing: hard, jump, J and L, match, cutaway, cross-cut, and smash cut. What each does, and how to build them.
Dip to black transition: fade out and in between clips
A dip to black fades one clip out to black, then fades the next in from black. How to build one when a render's fade is a crossfade, and the limits.
23.976 vs 24 fps: the difference and when it matters
23.976 fps is 24000/1001, the NTSC-film version of 24 fps: 0.1% slower, one frame in 1,001. When that gap matters, and what Sume renders do with it.
Keyframe interval explained: I-frames, GOPs, and cuts
The keyframe interval is how far apart a video's whole-picture frames sit. It decides where copy cuts and fast seeks land. How to read and set it.
How to convert frames to seconds (and back) at any fps
Seconds = frames ÷ fps, and frames = seconds × fps. How to convert frames and timecode at 24, 23.976, or 29.97 fps, and why Sume takes seconds.
What codec does MP4 use? MP4 is a container, not a codec
MP4 isn't a codec: it's a container holding video and audio compressed by separate codecs, such as H.264 and AAC. How to tell them apart.
How to check a video's codec with ffprobe or an API
Check a video's codec by probing it: ffprobe prints each stream's codec_name. For a Sume-hosted file, a free probe returns video_codec and pix_fmt.
MP4 plays audio but no video? Check the video stream
An MP4 that plays sound but no picture has a video stream the player can't decode, or none at all. Probe the codec and pixel format, then re-encode.
Convert 4:3 to 16:9 video: pillarbox, crop, or stretch
Convert 4:3 video to 16:9 three ways: pillarbox it, crop 12.5% off the top and bottom, or stretch it. With FFmpeg and the Sume API.
Cinematic bars size: bar height for 2.39:1 and 2.35:1
Cinematic bars on a 1920×1080 video are 138 px each for 2.39:1 and 131 px for 2.35:1. The formula, sizes for 720p to 4K, and how to add them.
How to find the aspect ratio of a video (and calculate it)
Find a video's aspect ratio by dividing its width and height by their greatest common divisor: 1920×1080 is 16:9. Plus the traps that mislead.
Vertical video resolution: 9:16 sizes from 720p to 4K
Vertical video resolution is 1080×1920 for 1080p, 720×1280 for 720p, and 2160×3840 for 4K. How to size any 9:16 frame, and what Sume can render.
How to upscale video to 4K: scale factors and step order
To upscale video to 4K, enlarge it by 2160 ÷ its height: ×2 from 1080p, ×3 from 720p. How to do it with FFmpeg or Sume, and why to upscale last.
Video freezes but audio continues: causes and fixes
If a video freezes but the audio continues in every player, the file holds a still frame. How to check its streams, and the three Sume render causes.
How to combine photos and videos into one video
Combine photos and videos into one video on a single timeline: each photo held for a set time, each clip cut to length, one soundtrack under it all.
What is text-based video editing? How transcript cuts work
Text-based video editing cuts a video by deleting words from its transcript. How word timings become a cut list, and how to build it with Sume's API.
AI image generator with a transparent background: 2 steps
Make an AI image with a transparent background in two steps: generate it on a plain backdrop, then remove the background to get a PNG with alpha.
Can a JPG be transparent? No: make a transparent PNG instead
No. A JPG has no alpha channel, so every pixel is opaque. Cut the subject out and save it as a PNG, a format that can store transparent pixels.
What size is 16:9 in pixels? Common 16:9 and 9:16 sizes
16:9 is a shape, not one size: 1280 × 720, 1920 × 1080, 2560 × 1440 and 3840 × 2160 are all 16:9. How to work out any size, and how to make one.
Twitter video ad specs: X Ads sizes, length, and file rules
X recommends video ads of 15 seconds or less, up to 1 GB (ideally under 30 MB), H.264 at 29.97 or 30 fps, in six sizes from 9:16 to 1.91:1.
CTV ad specs: video rules from five streaming TV sellers
CTV sellers ask for 16:9 video, H.264 or ProRes, and two-channel audio, but each sets its own lengths and a bitrate floor from 5 to 15 Mbps.
Roku ad specs: video and audio rules for Roku Ads Manager
Roku ads must be 16:9, 6–92 seconds, .mov or .mp4 up to 1 GB, 23.98, 25 or 29.97 fps, 6 Mbps or more, with 48 kHz 2-channel stereo audio.
Hulu ad specs: Disney's video rules for Hulu and Disney+
Hulu and Disney+ ads must be 16:9 (1920×1080 preferred), H.264 or ProRes at 23.98–30 fps, with one two-channel audio track of 128 kbps or more.
Amazon Sponsored Display video specs: display ads with video
Amazon display ads with video, formerly Sponsored Display, take 16:9 at 1920×1080 or more, 6–45 seconds, up to 500 MB, and autoplay muted.
Amazon Sponsored Products video: specs and guidelines
Sponsored Products video takes 1–5 silent feature videos per product: 7 seconds or longer, 16:9 (1920×1080 recommended), MP4 or MOV up to 500 MB.
YouTube Masthead specs: video size, autoplay, and captions
A YouTube Masthead plays a Public or Unlisted YouTube video, ideally 16:9 at 1920×1080 or higher, and autoplays muted for up to 30 s on desktop.
Social media video sizes: 8 platforms in one table
Vertical 9:16 is the video shape most platforms list. The sizes TikTok, Instagram, Facebook, YouTube, Snapchat, X, LinkedIn, and Pinterest give.
YouTube video size: 16:9 resolutions and upload settings
The standard YouTube video size is 16:9, and 1080p is 1920×1080. Every 16:9 size and bitrate YouTube recommends, and its 256 GB upload limit.
LinkedIn video size: dimensions, length, and file limits
A video in a LinkedIn post can be 256×144 to 4096×2304 pixels, 1:2.4 to 2.4:1, 75 KB to 5 GB and up to 15 minutes long. How to render one to fit.
Google Ads image sizes: 1200×628, 1200×1200, and 960×1200
Google's most common ad image sizes are 1200×628 (1.91:1) and 1200×1200 (1:1), plus 960×1200 (4:5) for Performance Max, as JPG or PNG up to 5,120 KB.
LinkedIn ad image size: 1200×628, 1:1, and 4:5 specs
LinkedIn recommends 1200×628 for single image ads, 1200×1200 for square and 720×900 for 4:5, as JPG, PNG or GIF up to 5 MB. Carousel cards: 1080×1080.
Etsy banner size: big and mini shop banner dimensions
Etsy recommends 1600×400 px for a big shop banner (1200×300 minimum) and 1600×213 for a mini banner. Logo sizes, file types, and a 4:1 AI banner.
Google Play feature graphic size: 1024×500 requirements
A Google Play feature graphic must be 1024×500 px, a JPEG or a 24-bit PNG with no alpha, and you need one to publish. The rules, and making the art.
Steam capsule sizes: header, small, main, and vertical
Steam's capsules are 920×430 (header), 462×174 (small), 1232×706 (main) and 748×896 (vertical). What each may show, and how to make the art at size.
YouTube watermark size: 150×150 minimum, under 1 MB
YouTube's video watermark must be a square image of at least 150×150 pixels and under 1 MB. When it shows, where it's hidden, and how to make one.
Transcribe long audio files: split into 10-minute parts
To transcribe long audio by API, split it into parts of up to 10 minutes, transcribe each part, then add each part's start time to its timestamps.
Transcribe video to text with an API: send the audio track
Transcribe video to text by API: send the audio track to speech-to-text. On Sume, inspect a Sume-hosted clip or send your own file's audio to STT 1.0.
Detect language from audio with a speech-to-text API
Detect the language spoken in an audio file: run speech-to-text with no language hint, then read the detected code and confidence from the result.
Korean speech to text API: transcribe Korean audio
Transcribe Korean speech to text by API: send the audio URL with language_code ko, or let it auto-detect, and get the transcript with word timings.
How to calculate speech rate in words per minute
Speech rate is words spoken divided by speaking time in minutes. Word timestamps from speech-to-text measure both, per recording or per sentence.
Translate audio to English: transcribe, translate, speak
Translate audio to English in three steps: transcribe the recording with language detection, translate the text, then voice it with TTS if needed.
Lip sync AI for long videos: past the 5-minute clip limit
To lip sync a long video with AI, split the audio, sync each part to the same face, and join the clips. One Sume job takes up to 300 s of audio.
How to burn an SRT file into a video
Burning an SRT file draws its lines into the picture. Sume's captions API takes no .srt file, so turn each block into a cue and send the cues instead.
How to generate an SRT file from a video
To generate an SRT file from a video, transcribe it with timestamps and write each timed sentence as a numbered block. Sume's STT returns timed JSON.