api.video lets you quickly and securely deliver on-demand and live-stream videos directly from your website, software, or app. 

api.video

Glossary-Hosting.svg

## What is Video Hosting?

Hosting definition: In the summer of 2021, Tokyo and Japan *hosted* the 2020 Summer Olympics. The country created facilities for thousands of athletes to come visit and compete in their respective events. The hosts of the Olympics made sure that everything was working, operational and ran smoothly. 

## Video Hosting

The concept of video hosting is similar. A video host [ingests](https://api.video/what-is/ingest/) videos, and hosts the files on their servers, ensuring that the videos are ready for playback. 

There are a number of options for video hosting - using a service, or self-hosting your videos.

### Self hosting video

Self hosting is the process of placing the videos on your own server for playback.  The advantage is that you control all of the aspects of your server.  The disadvantage is that videos are large - taking up a lot of server storage, and the transmission can also become quite expensive. You also cannot leverage the experience of a team of video delivery experts (who all generally work at video hosting services.)

### Video hosting services

Video hosting services include YouTube, Vimeo and (of course) [api.video](https://api.video). When working with a video hosting service, you can leverage the experience of video delivery experts to deliver your video - not only saving your bandwidth and storage, but also engineering and development time - since you do not have to create a pipeline for video upload, storage and delivery.

Advantages of video hosting services - Your video is typically converted into the best formats for a large number of viewers. Additionally, the video host will have optimized their infrastructure for the delivery of video. This typically includes low latency drives and memory to quickly deliver the data to the network. The videos are also cached around the world with e Content Distribution Network (CDN) to further lower the video delivery time. 

Some free services will watermark your video, insert ads or place other limitations on the video playback. A paid service like api.video will host your video in the optimal streaming formats, and deliver it for fast, low latency, no buffering playback to all of your users around the world.

## Hosting Summary

A video host is a server on the internet that is used to deliver video. There are specialized video delivery teams that have worked to optimize all aspects of video delivery - making your content shine, while simplifying your workflow.




Glossary-HTTP-Live-Streaming-HLS.svg

## What is HTTP live streaming (HLS)? 

HTTP Live Streaming (HLS) is a type of video streaming created by Apple. Despite the name, HLS streams can be recorded video ([video on demand](https://api.video/what-is/vod-video-on-demand/)) or live streamed.  HLS is the primary form of video streaming used on the web today, followed by MPEG-DASH.
 
Video streaming is different from a regular video in that the video is broken into smaller segments - typically 2-10s each, and are downloaded to a video player for playback.  
 
The segments are defined by a manifest file - which tells the player which files to request and how long each segment is - so the player can queue up and make the requests in a way that ensures that the video will always have enough video downloaded  - preventing the video from stalling.
 
HLS streaming can also support adaptive bitrate streaming. In this case, the same video is encoded at many different sizes and bitrates (smaller sizes have lower bitrates), and the player can adapt the video playback for the screen and for the available network speed.
 
All videos uploaded to api.video are encoded into a HLS video stream for playback. For more detail into HLS, and how each manifest file works, please read [What is HLS Video Streaming and How Does it Work](https://api.video/blog/video-trends/what-is-hls-video-streaming-and-how-does-it-work/).

Glossary-image-to-video.svg

## What is Image to Video?

Image to Video is an AI-powered technology that transforms static images into dynamic video content. This innovative application combines [Computer Vision](https://api.video/what-is/computer-vision/) techniques with video generation algorithms to create motion and temporal progression from still visual inputs. It's a subset of [Generative AI](https://api.video/what-is/generative-ai/) that bridges the gap between static and moving imagery, enabling the creation of video content from single or multiple image sources.

## Key Components of Image to Video Systems
Image to Video systems typically involve several key components:
1. Image Analysis: Understanding the content and structure of the input image(s)
2. Motion Estimation: Predicting plausible movements for elements in the image
3. Frame Generation: Creating intermediate frames to produce smooth motion
4. Background Reconstruction: Extending or recreating background elements as needed
5. Temporal Consistency: Ensuring coherent movement and changes across frames

## Techniques Used in Image to Video
Several AI techniques are crucial for Image to Video technology. Convolutional Neural Networks (CNNs) play a key role in analyzing and understanding the content of input images. Generative Adversarial Networks (GANs) are employed to create new video frames based on the input image.

Optical Flow Estimation is used to predict the motion of objects between frames, while Inpainting techniques fill in missing parts of the background revealed by object movement. Video Interpolation is also utilized to generate intermediate frames for smoother motion. These techniques work in concert to transform static images into dynamic video sequences, each contributing to different aspects of the conversion process.

## Applications of Image to Video
Image to Video technology has numerous potential applications across various fields. In social media, it can be used for content enhancement, bringing still photos to life for more engaging posts. Historical visualization benefits from this technology by animating old photographs to create more immersive historical experiences. In education, it serves as a powerful tool for creating dynamic visualizations from static diagrams or illustrations.

The advertising industry can leverage this technology to transform product images into eye-catching video advertisements. For tourism, it enables the generation of flythrough videos from landscape or architectural photos, offering virtual tours. In the film and animation industry, Image to Video technology assists in pre-visualization or creates dynamic backgrounds from still images. These diverse applications demonstrate the versatility and potential impact of Image to Video technology across multiple sectors.

## Challenges and Considerations
Image to Video technology faces several challenges:
- Realistic Motion Generation: Creating natural and plausible movements for objects in the image.
- Handling Complex Scenes: Accurately animating images with multiple objects or intricate details.
- Temporal Consistency: Maintaining coherent object appearance and movement across generated frames.
- Background Reconstruction: Convincingly filling in areas of the background revealed by object movement.
- Ethical Considerations: Addressing concerns about the authenticity of generated video content.

## The Future of Image to Video
As Image to Video technology continues to advance, we can expect several exciting developments:
- Improved Realism: Generation of increasingly natural and complex motions from still images.
- Enhanced User Control: More precise control over the type and extent of motion in the generated videos.
- Multi-Image Input: Creating more complex videos by intelligently combining multiple input images.
- Real-time Processing: Faster algorithms enabling on-the-fly video generation from images.

&nbsp;  

Integration with Other AI Technologies: Combining with [text to image](https://api.video/what-is/text-to-image/) or audio generation for more comprehensive content creation.

As Image to Video technology evolves, it has the potential to revolutionize how we interact with and create visual content. From bringing personal photos to life to creating dynamic visual effects for film and television, this technology opens up new possibilities for creative expression and storytelling. However, it also raises important questions about the nature of visual media and the need for transparency in content creation.

Glossary-ingest.svg

Definition of ingestion
- Food: When you ingest food, you are taking food into your body by swallowing it. Your body then processes the food into energy.
- Videos: Ingestion of a video is the process of uploading the file, and processing the video for playback.

## What is video ingestion?

After the video is uploaded, a video encoder will convert the uploaded file into versions that are available for playback.  This step is important as not all video formats can be played on every type of device. For example, iPhone videos are often recorded in h.265 HVEC - which is not widely supported outside of Safari and Apple products. In the conversion step, the video is created in enough formats to support universal playback (oftentimes this is h.264 - not the best compression, but the widest playback support).
 
 ## Video ingest at api.video
 
At api.video - video ingestion occurs when a video is created, and then the video file is uploaded into the video.  Once the file has been uploaded, api.video converts the video into 6 HLS video streams of differing sizes and bitrates, and a h.264 [mp4](https://api.video/what-is/mp4/) video file.

When the video is being ingested, you can query the ingestion process using the [video status](https://docs.api.video/vod/show-video-upload-status) endpoint:

```
"encoding":{
"playable":true
"qualities":[
{
"quality":"360p"
"status":"encoded"
}
{
"quality":"480p"
"status":"encoded"
}
{
"quality":"720p"
"status":"encoded"
}
{
"quality":"1080p"
"status":"encoding"
}
{
"quality":"2160p"
"status":"waiting"
}
```


You can also use the ```video.encoding.quality.completed``` [webhook](https://docs.api.video/reference/api/Webhooks) to understand when the video ingestion has completed for a given video at every quality it is encoded into.





## What is an Instant Replay?

Instant replay is the ability to retransmit a segment of video that was initially transmitted live.

The most common uses for instant replay is in sporting matches where a spectacular play or score is retransmitted after the fact.  Often different angles and speeds are used to watch the replay of the action - providing more information and insight into how the action unfolded.

In many sporting events, if the call by the on-field referee or judge is contested, instant replay can be utilized.  A judge with access to the myriad views and camera angles can replay the action in question to see if the call was warranted or if the video evidence shows that the call should be overturned.

## DVR/Instant replay at api.video

All of our live streams have 5 minutes of video stored on the server.  The api.video player has a rewind button that allows viewers to 'rewind' the live stream to rewatch any content that they would like to see again - essentially allowing for 'instant replay' opf anything being recorded on out platform.
- Read more about [instant replay/DVR](https://api.video/blog/product-updates/dvr-features-in-live-streaming/)
- See how we watched the [DVR replay of our snowman falling over](https://api.video/blog/video-trends/do-you-want-to-stream-a-snowman/)

Glossary-HDR.svg

## What does HDR stand for?

High dynamic range, normally abbreviated to “HDR”, is a term that originated in photography but quite quickly found its way into filmmaking. As an overview, “dynamic range” relates to the ratio between the smallest and largest values that an image or sound can be reliably transmitted. Within imagery (including video), it is essentially the extent to which its brightest and darkest regions can differ while still looking good.

HDR then extends that range to a much further extent. It is used to heighten contrasts between the darkest blacks and the brightest whites in order to bring an image’s color closer to its real-life details.

## What is HDR video?

In an attempt to provide a more photorealistic video-watching experience, HDR video technology has been developed to achieve that experience. HDR video is the next step in reproducing exactly what tends to be perceived by the naked eye into video form.

The process of creating photorealistic video begins, naturally, from the camera and will follow through to the post-production process of color correction before finally being shown on HDR-capable displays.


## What is the H.265 video codec?

H.265 is a video compression standard that offers 25-50% better data compression than H.264 while maintaining the same level of video quality. To achieve this incredible improvement, it extends on concepts found in the [H.264 codec](https://api.video/what-is/h-264/). A key difference from AVC (or H.264) is that H.265 uses more types of transforms and block sizes to achieve compression. H.265 is a fantastic choice if you want to stream and display high resolution video like 4K or higher. 

## How does the H.265 video codec work?

The H.265 video compression codec works by improving upon techniques that made H.264 so good. Recall that for the H.264 codec, video frames are broken into blocks. Each block is referred to as a macroblock, and these can vary in size. In the H.264 codec, blocks can range from 16x16 to 4x4 depending on the part of the compression process. The encoder makes a guess about what will happen in each block using intra and inter frame prediction Intra frame prediction happens within the same frame of video. The encoder tries to guess from surrounding pixels what will be present. Inter frame prediction looks at surrounding frames to determine what the difference is between the current frame and surrounding frames. 

Whether intra or inter prediction is being used at a given time, the encoder always breaks information into blocks. A big deal for the H.264 codec was the encoder being able to choose blocks of different sizes. For inter frame prediction, the encoder can choose blocks ranging from 16x16 to 4x4. For intra frame prediction, blocks are usually either 4x4 or 16x16 pixels wide. 

All of this changes with the introduction of the H.265 codec. In the H.265 codec, discrete cosine transform (DCT) is used for pixel blocks of 4x4 and 8x8. However, this codec ups the ante by ALSO using discrete SINE transforms (DST). It transforms block sizes from 4x4 to 32x32. This is for inter prediction. For INTRA prediction the H.265 codec can handle blocks of up to 64x64 pixels! These are more efficient ways of compressing the data, resulting in an up to 50% better data compression rate while still maintaining the same level of video quality or better. 

## What is the difference between H.265 and H.264?

There are a number of [differences between H.265 and H.264](https://api.video/blog/video-trends/H264-vs-H265/) codecs, here's a list: 
* H.264 is used almost everywhere in the world for video and can play on almost any browser. H.265 on the other hand only plays in about 18% of browsers. 
* For inter prediction, H.264 uses blocks ranging from 16x16 to 4x4. H.265 uses blocks that range from 32x32 to 4x4. 
* For intra prediction, H.264 uses blocks that are either 16x16 or 4x4 pixels wide. H.265 can use a complete range of blocks from 64x64 pixels all the way to 4x4. 
* H.265 can compress data up to 50% as much as H.264 without reducing quality.
* H.265 uses less bandwidth than H.264, allowing for higher quality video.


## Which is better: H.264 or H.265?

If you want to be sure your video plays when you send it out across the internet, you choose H.264. While it's not as efficient a codec, it's free and browsers nearly everywhere support the decoder for H.264. If you can afford to use H.265 (it's not free) and you know you're going to use a player that can handle H.265, then H.265 is the best choice. You will run into an issue with browsers still, because many browsers don't support H.265 due to the cost. While H.265 is great, it's also patent encumbered, driving up its cost of use.

Over time, a new codec will replace both these options. There are a few options in the works that will allow for a super efficient, high quality codec that's free and plays on every device. Some examples are H.266, VP9 and AV1, but one has not yet emerged as the leader. VP1 and AV1 are competitors with one another and H.266 is the next generation of H.265. All promise to be less patent encumbered and free. We'll just have to wait and see! 


Glossary-H-265.svg

thumbnail_h265.jpeg

h265.jpeg

Glossary-H-264.svg

## What is the H.264 codec?
H.264 is a video compression standard that's currently the most widely used codec on the planet. It uses advanced algorithms for estimating motion, inter-prediction, spatial intra-prediction and discrete cosine transfer (DCT) coding. It can be used for discs like Blu-ray (and others), broadcast and video streaming. This codec is also compatible with a lot of different container formats like MP4, MOV, 3GP, MPEG and F4V. Audio is compressed separately, usually using the [AAC (advanced audio coding)](https://api.video/what-is/aac-advanced-audio-coding/) standard. 

## How does the H.264 codec work? 
H.264 has an encoder and a decoder as part of the codec. The encoder handles prediction, transform and encoding tasks in order to efficiently compress a video file. 

Prediction is where the encoder takes a single frame of a video at a time and breaks it into blocks. Each block is called a macroblock, and these can vary in size by codec or method used to handle the blocks. Typically for H.264, the encoder breaks blocks into groups of between 16x16 and 4x4 pixels, but it could be different. The encoder then guesses what's going to be in the block, using these techniques: 
* **Intra prediction** - the encoder uses the way things are set up directly in the image to guess what other pixels in the image might be. For example if you're in a shadowy part of the image, the encoder might guess that there are more dark pixels in that area. Blocks for this type of prediction are either 4x4 or 16x6 pixels high and wide.
* **Inter prediction** - the encoder looks at a previous frame, then subtracts whatever is the same and keeps only the differences in the new frame for storage. This is called forming the residual. Blocks for this type of prediction can be anything from 4x4 to 16x16.

h-264.jpg

The transform task is where the encoder takes the information its saved and transforms it into a matrix of values where the positions in the matrix correspond to pixels at specific positions in the image. To do this, it uses a Fourier-transform. Since this article is about H.264, we won't get into too much detail. Suffice it to say the transform is going from an image to a matrix that represents the pixels to a wave. You're transforming the information into something that can be modeled using waves. This is easier to store and transfer, because once you can model your image using waves, you can come up with a way to represent the signal as the sum of combinations of cosine waves.  

## What is the difference between an MP4 and an H.264 file?
MP4 is a container format and stands for MPEG-4 Part 14. It's the most popular video format in the world because it allows you to combine all sorts of media - video, audio, subtitles and images. Most devices will play an MP4 and today many sites choose MP4 above other formats, making it everyone's go to choice. MP4 is different from H.264 because MP4 is a file format and H.264 is a codec. A file format describes what kinds of information can contain and how it will be organized. A codec describes how video or audio (or both) will be compressed and decompressed later for playback.

## Which is better: H.264 or H.265?
To determine whether [H.264 or H.265](https://api.video/blog/video-trends/H264-vs-H265/) is better, you must choose your criteria. For quality and speed, [H.265](https://api.video/what-is/h-265/) is better. For price, H.264 is free. There are more instances where you may use the H.264 codec free of charge for your video content. H.265 on the other hand, must always be paid for. Because of this, there is less support for H.265. If you want good quality and speed, and the ability to play back your video almost anywhere for free, choose H.264. Companies like Netflix and Hulu earn enough money that they can benefit from paying for H.265 to deliver a higher quality more efficient video experience. 

New codecs are under development to replace both of these, with the goal of the codecs being more efficient, providing higher quality, and being free. 

## What is the H.263 video codec?

The H.263 video codec was designed for teleconferencing video compression. It could be compressed and sent at a low bitrate. The video quality wasn’t great, but it was efficient for videoconferencing. Today, while this codec is obsolete, it’s still included in videoconferencing systems along with H.261 for occasions when it might be required. H.263 was revamped several times, so that in addition to videoconferencing, it ended up being used in the early days to display Flash video on the internet. 

## How is H.263 different from H.261 and H.262? 

The H.263 video codec is an evolutionary improvement on the algorithms and techniques that were started with H.261. A key difference is that it handles low bit-rates better than previous codecs in the H.26x family. It keeps a lot of the main design features like the discrete cosine transform (DCT), use of transform coding for intra-frames and predictive coding for inter-frames. It uses more advanced techniques to compress macroblocks. It also does a better job of smoothing out compressed blocks so they are smoother when decompressed for playback. Something unique is the introduction of the B frame. 

Previously, video frames were compressed using techniques that involve I and P frames. An I-frame is a type of compression where everything references only the frame you're looking at. It's a key frame that other frames might reference. A Prediction frame (P-frame) is a frame that predicts where objects and things may have moved to from the I-frame. Up until H.263, these are the types of frames used. H.263 adds the B or Bi-Directional frame. This type of frame is similar to a P-frame, but they can predict where an object will be by looking into the past frames or into the future frames. They're efficient because they have more options for how to compress data temporally and spatially but they're resource heavy because it takes more work to calculate them. If a frame needs details from a frame that comes before and after it in order to encode, you have to wait to get those frames before encoding. So it's a bit more complex since now the frames aren't processed in the order they appear in. 

## Conclusion
H.263 went through three major revisions and was widely used for video conferencing and internet videos until the creation of H.264. Now H.263 is included just in case it's still needed for old systems, but most of the time H.264 or higher is going to be used. 

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