If you are using Larix Broadcaster for YouTube Live, start with a 2-second keyframe interval and choose the bitrate for your actual resolution and frame rate. For H.264, YouTube’s starting points include 4 Mbps for 720p30, 6 Mbps for 720p60, 10 Mbps for 1080p30 and 12 Mbps for 1080p60.
Those figures are targets, not guarantees that every mobile connection will carry the stream reliably. Match the setting to the upload speed you can sustain, test with the same kind of audio and movement as the real broadcast, and watch YouTube’s stream health once you go live.
Set Larix’s keyframe interval to two seconds
A keyframe is a complete video image. The frames between keyframes usually describe changes from an earlier image, so the encoder does not need to send every frame as a complete picture. A regular keyframe pattern helps YouTube process the incoming stream and gives viewers a sensible point at which playback can begin or recover.
YouTube’s encoder guidance recommends a 2-second keyframe interval and says not to exceed 4 seconds. In Larix, use 2 seconds if the control is expressed in seconds. If the app offers a frame count instead, convert the interval using the selected frame rate.
Do not treat the 4-second figure as a preferred setting. It is the maximum stated in the guidance, not a reason to select a longer interval when 2 seconds is available. You can check the current requirements in YouTube’s live encoder settings, because platform guidance and app controls can change.
The keyframe interval is separate from bitrate. Increasing the bitrate does not correct a keyframe interval that is too long, and changing the keyframe setting does not give a weak mobile connection more upload capacity. Set both deliberately.
For a devotional phone stream showing a mostly fixed image, two seconds is still the sensible starting point. A still background may be easy to encode, but viewers and YouTube still receive a live video stream with its own timing requirements. For a local news loop with camera movement, scrolling text or transitions, the same interval gives the encoder regular complete frames while the rest of the picture is sent as changes.
Convert seconds into frames for your frame rate
Some encoder controls ask for a duration in seconds. Others ask for the number of frames between keyframes. The conversion is straightforward:
keyframe frames = seconds × frames per second
For YouTube’s 2-second starting point:
| Selected frame rate | Calculation | Equivalent keyframe setting |
|---|---|---|
| 30 fps | 2 × 30 | 60 frames |
| 60 fps | 2 × 60 | 120 frames |
At 24 fps, the arithmetic equivalent is 48 frames. At 25 fps, it is 50 frames. These are mathematical conversions, not claims about a particular Larix release or device interface. If your app shows a seconds control, entering two seconds avoids having to manage the equivalent frame count yourself.
Use the frame rate that the outgoing stream actually uses. If your source is recorded or composed at 30 fps but you select 60 fps in the output settings, calculate from 60 fps. A 60-frame interval at 60 fps is one second, not two, so copying a frame count from a 30 fps setup changes the interval.
The same principle applies to the stated maximum. Four seconds would be 120 frames at 30 fps and 240 frames at 60 fps. Those conversions do not turn the maximum into a recommendation. They simply show why a frame-count setting must be considered alongside the selected frame rate.
Before starting a long broadcast, look at the saved profile rather than relying on memory. Confirm the output frame rate, bitrate, codec, audio settings and keyframe value together. A profile copied from a 30 fps landscape stream may not be correct for a 60 fps sports clip or a portrait phone layout.
Choose a bitrate starting point by resolution and frame rate
Bitrate is the amount of encoded data sent over time, usually shown in bits per second. Resolution describes how many pixels are in each image, while frame rate describes how many images are sent each second. Both affect the amount of video information the encoder needs to represent.
YouTube’s H.264 recommendations give these useful starting points:
| Output video | YouTube H.264 starting point | Practical implication |
|---|---|---|
| 240p–720p at 30 fps | 4 Mbps | A lower-resolution or 720p30 stream with modest motion |
| 720p at 60 fps | 6 Mbps | More frames each second, so a higher target than 720p30 |
| 1080p at 30 fps | 10 Mbps | More pixels than 720p, even at the lower frame rate |
| 1080p at 60 fps | 12 Mbps | More pixels and more frames each second |
| 1440p at 30 fps | 15 Mbps | Higher-resolution output with a larger data requirement |
| 1440p at 60 fps | 24 Mbps | Higher resolution combined with a higher frame rate |
| 2160p at 30 fps | 30 Mbps | 4K output at 30 fps |
| 2160p at 60 fps | 35 Mbps | 4K output at 60 fps |
These are starting points from YouTube’s H.264 table, not universal Larix requirements and not a promise that a connection will sustain them. Use the row matching the actual output resolution and frame rate. Do not set every stream to 10 Mbps simply because that value appears beside 1080p30.
For many phone-based broadcasts, the most useful comparison is between 720p30 and 1080p30. Moving to 1080p increases the visual detail and the recommended bitrate, but it also leaves less room for an unstable upload connection. If the picture contains a static devotional artwork, a study timer or a fixed ambience scene, stable 720p30 may be more useful than a higher setting that repeatedly drops data.
Frame rate matters even when the resolution stays the same. YouTube lists 4 Mbps for 720p30 and 6 Mbps for 720p60. The higher frame rate can make a moving camera, a scrolling ticker or a game look smoother, but it also raises the target. Select 60 fps because the content benefits from it, not because the number sounds better.
A third-party Larix guide from Gcore gives examples of 720p30 at 2 Mbps and 1080p30 at 4 Mbps, paired with a 60-frame keyframe interval. Those are Gcore service examples, not replacements for YouTube’s H.264 table or universal Larix settings. They illustrate that a service may publish a different operating example for its own circumstances; they do not establish that 2 Mbps is enough for every 720p30 YouTube stream. The examples are documented in Gcore’s Larix guide.
Match quality to sustainable mobile upload
The correct bitrate is not the highest number your speed-test result displays for a few seconds. It is a rate your connection can maintain while the phone is in the place and condition where you will actually broadcast.
Mobile upload can change with location, network congestion, indoor signal, movement between cells and other traffic on the connection. A speed test made beside a window in the afternoon may not describe the upload available at the temple, shop, classroom or outdoor event where the stream will run. If the channel is intended to stay live overnight, test during a period that resembles the overnight conditions rather than testing only when the network is quiet.
YouTube advises testing the connection and selecting a quality that is reliable on the available connection. Start with the resolution and frame rate you want, then check whether the upload remains steady at the corresponding bitrate. Leave headroom for normal variation rather than planning to use every last part of the measured upload capacity.
The bitrate in the table is video bitrate. The stream also has audio and protocol overhead, so the connection needs to carry more than the video number alone. The exact margin depends on the encoder and network, which is another reason to validate the complete setup instead of judging it from a headline speed-test result.
If 1080p30 at 10 Mbps produces buffering, dropped frames or warnings, changing to 720p30 at 4 Mbps may be the honest fix. It is not a failure to choose a lower output. For an always-on 24/7 fireplace or ambience channel, viewers may notice interruptions more than they notice the difference between two resolutions.
The same trade-off applies to a small business or local news loop. A clear, stable 720p feed with readable text is more useful than a nominally sharper stream whose upload collapses whenever customers enter the shop or the mobile network becomes busy. Test the smallest important detail, such as a ticker, menu, timetable or subtitle, at the selected resolution before committing to it.
When you change resolution or frame rate, revisit the whole profile. The bitrate, keyframe frame count and connection test are related. Do not lower the frame rate while leaving a frame-count keyframe value unchanged without checking the resulting interval.
Configure the rest of the Larix profile
Bitrate and keyframes do not work in isolation. YouTube’s guidance lists CBR encoding and RTMP or RTMPS streaming. It recommends RTMPS, which is the encrypted extension of RTMP. Where Larix and your device offer the relevant choices, use the YouTube-compatible configuration and confirm that the stream key and server details have been entered correctly.
For a straightforward Larix-to-YouTube setup, H.264 is a practical baseline when it is available on the device. YouTube lists H.264, H.265/HEVC and AV1 as video codec options, but the choices exposed by Larix depend on the app version and device. Do not select a codec merely because the platform lists it. Check what your phone can encode consistently and what the Larix profile actually sends.
YouTube lists AAC or MP3 for audio in its RTMP/RTMPS guidance, with AAC specified for 5.1 surround. Its listed stereo audio setting is 128 Kbps. For a devotional stream, meditation music or a lofi station, audio quality and continuity may matter more to the listener than a jump from 720p to 1080p, so include the audio path in your test rather than checking the picture alone.
Write down the profile that passes your test. Record the output resolution, frame rate, video bitrate, codec, audio setting, transport and keyframe interval. This gives you something to restore after an app update or accidental change. It also makes troubleshooting less circular: you can identify which setting changed instead of changing several at once.
If you are planning a longer, unattended channel, compare the work involved in keeping a phone available with a cloud-based workflow. A guide to what cloud playout means can help you distinguish a live camera setup from sending a prepared file continuously. StreamNeo is useful when the specific problem is leaving your computer switched on to keep an uploaded video running, because the file and YouTube connection can continue without that computer being left on.
That does not remove the need to check the video, audio, rights and YouTube channel settings. It only addresses the particular operational problem of keeping a prepared stream running when a personal device would otherwise have to stay active.
Test with representative audio and motion
A test should resemble the broadcast, not merely prove that Larix opens the camera. Include the same output resolution, frame rate, bitrate, audio source and transport you intend to use. If the real stream will run from a mobile connection, test on that connection from the same location where possible.
Include the content that creates the most useful encoding evidence. For a music or devotional channel, play the actual audio chain and include the artwork, lyrics, subtitles or transitions that viewers will see. For a local news loop, include scrolling text, lower-thirds, cuts between clips and any camera movement. For a study channel, test the smallest text and timer digits at the chosen resolution. For ambience, include the movement that is easy to miss in a still preview, such as rain, flames, water or a slow camera pan.
Listen with headphones and watch on another device if you can. Check that speech, music and background audio are present, that the audio is not distorted, and that the picture and sound remain aligned. A stream can have a healthy-looking preview while the microphone is muted or an audio source is not the one you intended.
Run the test long enough to expose changes in the connection. The point is not to claim that a particular duration proves reliability. The point is to observe the stream under representative conditions rather than treating the first successful connection as evidence that an all-night broadcast will behave the same way.
Use YouTube’s test or private workflow where it fits your channel, and review the resulting stream on the viewer side. You can also follow the practical approach in this guide to testing a YouTube lofi radio stream before making it public. It is especially useful when the final audience will be listening for hours, because short preview checks can miss audio gaps and repeated connection problems.
Change one variable at a time. If you move from 1080p30 to 720p30, keep the keyframe interval and audio path fixed while testing the effect of the lower video requirement. If you change the network, repeat the test before drawing conclusions about the bitrate. This makes the result more informative than changing resolution, frame rate, codec and microphone together.
Monitor stream health during the broadcast
A successful start is not the end of the check. During the broadcast, monitor YouTube’s stream health and read the messages it provides. YouTube’s live streaming documentation includes warnings related to low bitrate and keyframe intervals that are too long, so these messages can point to a setting or connection problem rather than a vague feeling that the stream looks poor. The relevant API documentation is available in the YouTube Live Streams reference.
Look for a pattern. A brief change when the phone moves may suggest a network issue. Repeated low-bitrate warnings at a fixed setting may mean the connection cannot sustain the chosen target. Warnings about keyframes should send you back to the frame-rate and interval calculation, especially if you entered a frame count manually.
Also monitor from the viewer’s perspective. Confirm that the live page remains playable, the audio continues, the picture does not freeze and text remains readable. If you have a co-host or another person at the location, ask them to watch rather than relying only on the device carrying the broadcast. A phone can appear to be transmitting while the audience experience has degraded.
If the stream is unstable, prioritise continuity. Reduce resolution or frame rate and retest rather than repeatedly restarting the same profile. If the connection is strong but the image is soft, investigate the source, focus, lighting and encoder settings before raising the bitrate. More data cannot restore detail that was never captured.
For a 24/7 channel, create a simple check routine. Confirm the live page, listen for audio, inspect the latest health message and note any changes to the connection or app profile. Keep a record of what happened when the stream recovered or failed. Over time, that record is more useful than a single speed test because it reflects your actual location, schedule and content.
A practical starting profile
For a first Larix test, choose H.264 if that is the stable option your device exposes, use CBR if available for the YouTube profile, select RTMPS where supported, and set the keyframe interval to two seconds. Then choose the bitrate from YouTube’s row for your output resolution and frame rate.
A sensible first comparison is 720p30 at 4 Mbps versus 1080p30 at 10 Mbps. Test both only if your connection is likely to carry the higher setting. Include the real audio, movement and text. If 720p30 is stable and 1080p30 is not, keep 720p30 rather than assuming the connection will improve once the broadcast is public.
For 720p60, begin from YouTube’s 6 Mbps H.264 figure. For 1080p60, begin from 12 Mbps. At 60 fps, remember that a 2-second keyframe interval corresponds to 120 frames. These values remain starting points: your encoder, device, source material and mobile network determine whether the complete stream behaves well.
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FAQ
What bitrate should I use in Larix for 720p30 on YouTube?
YouTube’s H.264 guidance lists 4 Mbps for 240p–720p at 30 fps. Treat that as a starting point, then test whether your actual mobile upload can sustain the complete stream with audio and overhead. A lower, stable output can be preferable to a higher setting that drops data.
Should the Larix keyframe setting be seconds or frames?
Use two seconds when Larix provides a seconds-based control. If it asks for frames, two seconds equals 60 frames at 30 fps and 120 frames at 60 fps. YouTube recommends two seconds and says not to exceed four seconds.
Is 10 Mbps always enough for 1080p YouTube Live?
No. YouTube lists 10 Mbps as an H.264 starting point for 1080p30, while 1080p60 is listed at 12 Mbps. Neither figure guarantees reliable delivery on every device or connection, so test the selected frame rate and resolution on the connection you will actually use.
What should I do if YouTube reports low bitrate?
Check that Larix is sending the profile you intended, then inspect the upload connection and YouTube’s stream health messages. If the connection cannot sustain the selected setting, reduce resolution or frame rate and test again. Also confirm the keyframe interval, since a low-bitrate warning and a long-keyframe warning can point to different problems.