You can stream MP4 and MKV files in one FFmpeg playlist if their contained audio and video streams are compatible. The extensions alone do not determine compatibility: compare the streams, codecs, and time bases. If they differ, normalize or transcode the files to a shared profile before streaming. For compatible files, FFmpeg’s concat demuxer can read them sequentially and stream-copy their encoded packets.
Why mixed MP4 and MKV files may—or may not—work
MP4 and MKV are container formats: wrappers that hold encoded video and audio streams. Two files with different extensions can contain compatible streams, while two files with the same extension can contain incompatible ones. FFmpeg’s concat demuxer requires the files to have the same streams, including codecs and time bases; differences in stream layout or inaccurate duration metadata can also cause problems. See the FFmpeg concat demuxer documentation.
That means a playlist is not a conversion step. It tells FFmpeg to read files in sequence and adjust timestamps; it does not make unlike streams match.
Inspect the files before making the playlist
Use ffprobe on each file, or another media inspector, and compare the properties that affect compatibility:
Free tools Windows power users keep installed
One-click scans. No signup required.
#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.
- Number and type of video and audio streams
- Video and audio codecs
- Stream time bases
- Video dimensions, frame rate, and pixel format
- Audio sample rate, channel layout, and other audio parameters
Check the installed FFmpeg version’s documentation as well: online FFmpeg documentation can describe a newer revision than your local binary.
Create a concat-demuxer playlist
Make a plain-text playlist, saved as UTF-8, with one file entry for each clip in playback order. For example:
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.
file '/media/clip-one.mp4'
file '/media/clip-two.mkv'
file '/media/clip-three.mp4'For simple paths, a typical invocation begins like this:
ffmpeg -re -f concat -safe 0 -i playlist.txt ...The ellipsis is intentional: the output options depend on the codecs in your files, the installed FFmpeg build, and the ingest protocol and settings selected in YouTube Studio. -re reads the input at its native rate rather than as fast as possible. -safe 0 permits paths outside the concat demuxer’s restricted safe subset; use it only with a playlist you control. Consult the concat demuxer documentation for the supported script format and directives.
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.
Choose stream copy or normalize the files
Use stream copy when the streams are compatible
When inspection shows that the files have compatible streams and the output container can carry their codecs, try explicit stream mapping and stream copy. FFmpeg stream copy passes encoded packets through without decoding, filtering, or encoding them. It is fast and avoids re-encoding quality loss, but it cannot apply filters or repair incompatible streams, and it may fail if the target container cannot meet its requirements. Read FFmpeg’s stream-copy documentation.
Transcode or preprocess when they are not
If stream counts, codecs, time bases, or other relevant parameters differ, convert every item to a shared profile before playlisting. Re-encoding takes processing capacity and can affect quality; confirm that your machine can encode at the required rate. If filtering or other frame-level changes are needed, FFmpeg must decode the media. The FFmpeg concatenation FAQ explains the concat filter as an alternative when re-encoding is necessary. Do not assume -c copy makes mismatched files compatible.
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
Configure YouTube Live and send the playlist
- Choose the ingest settings in YouTube Studio. In Live Control Room, select the stream setup and copy its stream URL and stream key into your FFmpeg output configuration. Use the current settings shown for that stream; verify the selected protocol and supported codecs against your FFmpeg build and output container.
- Match the encoder to YouTube’s guidance. YouTube’s live-encoder guidance, accessed 2026-10-03, lists RTMP/RTMPS; H.264, H.265 (HEVC), and AV1 video; and AAC or MP3 audio. It recommends constant bitrate (CBR) and a two-second keyframe interval, which should not exceed four seconds. A conventional compatibility route is H.264/AAC in an FLV output, but check that your build and media support the actual configuration. See YouTube’s live encoder settings.
- Set a suitable resolution, frame rate, and bitrate. YouTube’s table lists these H.264 examples: 720p at 30 or 60 fps, 8 Mbps recommended and 3 Mbps minimum; 1080p at 30 fps, 14 Mbps recommended and 5 Mbps minimum; and 1080p at 60 fps, 17 Mbps recommended and 6 Mbps minimum. These are YouTube-published settings, not a guarantee that your upload connection can sustain them. Match the output to the source and your connection’s reliable capacity.
- Set the remaining picture and audio parameters. YouTube recommends 128 Kbps stereo audio, square pixels, progressive scan, and Rec. 709 for SDR. Confirm that your chosen output profile and source support the settings you select.
- Protect the stream key. Treat it like a password: do not share it or publish it in logs or scripts, and reset it if compromised. YouTube describes managing the key in Manage live stream settings.
- Test, then monitor stream health. Before the broadcast, send a representative section with typical audio and motion. Check Live Control Room for stream-health messages and monitor them while live. YouTube’s encoder guidance recommends testing before going live and monitoring stream health.
Common problems and what to check
- The playlist stops or errors at a file boundary: compare that file’s stream count, codecs, time bases, and other parameters with the rest. Normalize the mismatched items and try again.
- FFmpeg reports a container or codec error: verify that the output muxer supports the selected codecs. Stream copy cannot convert a codec or satisfy an incompatible target-container requirement.
- Audio or video changes unexpectedly between clips: compare the inputs’ audio and video parameters; create a consistent shared profile if they differ.
- The stream is unstable or YouTube reports poor health: check whether your connection can sustain the chosen bitrate, confirm the encoder settings shown in Live Control Room, and test with representative content before restarting the event.
- The playlist cannot open a path: check spelling, quoting, and file permissions. If using
-safe 0, ensure every playlist entry is trusted and under your control. - The stream key may have been exposed: reset it in YouTube Studio and update the FFmpeg configuration with the replacement.
Copyright and channel-policy checks
Having a playable file does not establish that you have the rights to broadcast it. Use content you created or are authorized to stream, and check YouTube’s current rules and any applicable rights restrictions before broadcasting. Technical compatibility also does not determine whether a channel’s content meets YouTube’s monetization or other channel policies; consult YouTube’s current policy guidance for your situation.
Or let it run in the cloud
If the goal is to keep uploaded videos playing as a YouTube live stream without leaving your own computer running, StreamNeo is a cloud option: upload a recording or build a playlist, add your YouTube stream key once, and go live. It loops uploaded videos; it does not broadcast a camera feed. Your computer and home connection do not have to stay on, and the service automatically recovers if YouTube drops the stream.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
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.
Each slot streams the uploaded quality up to 4K 60fps at one flat price per slot, with no re-encode or quality tiers. The first day is free with no card, one free day per account. Monthly pricing is $9.99 per month. UPI and cards are available in India; card checkout is available worldwide. Start your free day with StreamNeo.
Quick Recap
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.
