Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsTo make separate FFmpeg outputs begin at different points in their source videos, put a separate -ss before each input’s -i. Use -itsoffset only when you need to shift timestamps—not to choose a different scene or song. FFmpeg options are order-sensitive and generally apply to the next input or output.
Choose the option that matches what you mean by “start time”
| Goal | Use | Effect |
|---|---|---|
| Begin each source at a different scene, song, or media position | -ss before the corresponding -i |
Seeks that input to the requested position. |
| Delay or shift the timestamps of an input’s streams | -itsoffset before the corresponding -i |
Adds an offset to input timestamps; a positive offset delays the streams. |
| Start a scheduled broadcast at a wall-clock time | Not established by the FFmpeg options covered here | Neither option schedules a YouTube broadcast for a particular clock time. |
The documented output-side form of -ss seeks by decoding and discarding media until the requested position. For different starting positions in separate source files, input-side seeks are the direct approach.
Set a different media position for each input
- Identify the source file for each output and the media position where that output should begin.
- Put
-ssimmediately before that source’s-i, using the desired time inHH:MM:SSform. - After the input, map its video and audio streams and configure the codecs and output destination appropriate to your ingest protocol.
- Repeat for the next input. Use that input’s own seek value and its correct input index in any
-mapoptions.
This schematic command illustrates per-input seeks and mappings; it has not been tested. Replace the output destinations and codec settings for your actual workflow:
ffmpeg
-ss 00:02:00 -i inputA.mp4
-map 0:v? -map 0:a? -c:v libx264 -c:a aac OUTPUT_A
-ss 00:05:00 -i inputB.mp4
-map 1:v? -map 1:a? -c:v libx264 -c:a aac OUTPUT_BHere, the first output uses input 0 starting at 2:00, while the second uses input 1 starting at 5:00. The optional ? in the mappings allows a mapping to match when that stream type is present; check the source files and resulting output if a file lacks audio or video.
The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
Why option order matters
FFmpeg options generally apply to the next input or output file, and options reset between files. Keep each input’s -ss directly before its -i; placing it after an input changes its role. Likewise, a mapping refers to an input index, so confirm that each output is mapped to the intended source.
Use -itsoffset for timestamp alignment
-itsoffset is an input option. Place it before the matching -i to add an offset to that input’s timestamps. A positive offset delays the corresponding streams. It does not seek to a different content position, so use -ss when the opening scene or song needs to differ.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Do not confuse HLS variants with independent starts
Multiple HLS quality variants are renditions of one presentation, not separate broadcast schedules. FFmpeg uses stream mappings and var_stream_map to configure variants; when producing two or more variants, the output filename pattern must include %v. This creates rendition outputs, but does not by itself make each rendition begin at a different point in the content.
Starting within an incoming live HLS playlist
If the input is a live HLS playlist and the goal is to choose which segment to begin with, the HLS demuxer documents live_start_index. Negative indices count from the end of the playlist. The demuxer also documents prefer_x_start, which can prefer an #EXT-X-START tag in the playlist. These are input-demuxer behaviors, distinct from seeking through a local video file.
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
Check the YouTube ingest protocol
The output side of the schematic command must match the protocol selected in YouTube Live Control Room. The following requirements apply specifically to YouTube HLS ingest; confirm current settings in Live Control Room before configuring a production stream.
- Use TS segments lasting 1–4 seconds.
- Maintain a rolling playlist with no more than five outstanding segments.
- Send segments using HTTPS POST or PUT; byte ranges are not supported.
- Account for higher latency because HLS sends video in segments. YouTube’s Ultra low-latency option is turned off for HLS.
Do not assume that separate inputs and outputs in one FFmpeg command establish that YouTube permits multiple distinct broadcasts through one process or one stream key. That platform-specific case is not established here; verify the current YouTube workflow for your account and chosen ingest protocol.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Troubleshoot the common timing mistakes
- Both outputs appear to begin at the same point: Check that each
-ssappears before its own-iand that the values differ. - The wrong source appears in an output: Check input numbering in each
-map. In the example, input A is 0 and input B is 1. - The streams are delayed, but show the same content position: That is consistent with a timestamp shift. Use per-input
-ssto select different content positions. - HLS variants do not start at separate content positions: Variant configuration creates quality renditions, not independent starts. Configure separate source inputs and outputs if that is the intended workflow.
- An HLS output fails ingest: Check the segment format and duration, rolling playlist limit, HTTPS method, and byte-range behavior against YouTube’s HLS requirements.
- A local-file seek behaves differently from an HLS segment selection: Confirm whether the input is a file or a live HLS playlist; the demuxer’s
live_start_indexapplies to the latter.
Or let it run in the cloud
If your goal is to keep uploaded videos playing on a YouTube channel rather than configure multiple FFmpeg outputs yourself, StreamNeo runs the loop in the cloud: upload a recording or build a playlist, add your YouTube stream key, and go live. Nothing has to stay on at home. Any quality up to 4K 60fps streams as uploaded at one price per slot; there are no quality tiers or re-encoding. StreamNeo automatically recovers if YouTube drops the stream. The first day is free with no card. Monthly billing is $9.99 per month. StreamNeo plays uploaded videos and streams to YouTube; it does not go live from a camera. Start your free day with StreamNeo.
Quick Recap
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
