Is it possible to programmatically intercept video requests with Range headers, fetch the content, and store it as blobs in IndexedDB on the browser side for later serving?

Help & Support
1

Due to the substantial amount of MP4 content kept in the blob storage and my desire to avoid switching to HLS or DASH protocols, I’m looking for a way to persuade the video player to create a caching mechanism for downloaded video content. How can I encourage the gamer to use content caching effectively to solve this particular problem?

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2

Yes, it is possible to programmatically intercept video requests with Range headers, retrieve the content, and store it as blobs in the browser’s IndexedDB for later use. This method is frequently used in web applications to include offline playing and video caching.

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3

Thanks for your response!

Can you write a short tutorial on it for more clarification?

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4

Sure, follow the steps given below:

  1. Service Worker

    To start, use a background-running script that can intercept network requests called a Service Worker. It is frequently used for operations like request interception and caching.

  2. Request Interception

    To intercept video requests, keep an eye out for fetch events inside the Service Worker. Check to determine if the request contains a Range header, which usually appears in video streaming and denotes partial content retrieval.

  3. Utilize the get() API

    To obtain the desired video segment from the server after intercepting a request for a video that has a Range header. Use the response.blob() function to turn the response into a Blob after getting it.
    Storage with IndexedDB: Continue storing the Blob in the browser-based database IndexedDB. An asynchronous API for storing structured data, including Blobs, is provided by IndexedDB.

When the user wants to watch the video offline in the future, they should retrieve the saved Blob from IndexedDB. Use URL.createObjectURL() to make a blob URL, then designate it as the video element’s source.
For example,

self.addEventListener('fetch', event => {
  const request = event.request;
  const url = new URL(request.url);

  // Check if the request is for a video and has a Range header
  if (url.pathname.endsWith('.mp4') && request.headers.has('range')) {
    event.respondWith(handleVideoRequest(request));
  }
});

async function handleVideoRequest(request) {
  const response = await fetch(request);
  
  if (response.ok && response.status === 206) { // Partial content response
    const videoBlob = await response.blob();
    
    // Store the blob in IndexedDB
    const db = await openIndexedDB();
    await storeBlobInDB(db, request.url, videoBlob);
    
    return response; // Return the original response
  } else {
    return response; // Pass through for other cases
  }
}

async function openIndexedDB() {
  const db = await indexedDB.open('videoCache', 1);
  // Initialize the database schema if needed
  // ...

  return db;
}

async function storeBlobInDB(db, url, blob) {
  const transaction = db.transaction('videos', 'readwrite');
  const objectStore = transaction.objectStore('videos');
  
  await objectStore.put(blob, url);
}

Note: It’s essential to recognize that the provided code is a condensed form. More complex factors like error handling, cache management, data cleaning, and compatibility testing across different browsers and network circumstances are required in practical use. Also keep in mind that Service Workers have distinct quirks, especially in relation to range requests and video streaming. A robust implementation requires extensive testing and optimization.

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5

Great!

One more ques: What are the errors and challenges that can arise while implementing the above process?

7

Due to a number of difficulties and potential problems, implementing the process of capturing video requests, retrieving content, and storing it as blobs in IndexedDB might be complicated. Here are some common issues and mistakes that you could run into:

  1. Handling Partial Content

    Dealing with requests for partial content, which involves utilizing the Range header, can become convoluted. This complexity arises when the response headers from the server don’t align with your expectations. Ensuring that the server appropriately supports and responds to partial content requests is crucial.

  2. Content-Length Discrepancy

    There might be instances where servers fail to provide an accurate Content-Length header for partial content responses. This discrepancy can lead to problems when reconstructing blobs or managing content ranges.

  3. Overlapping Ranges

    If a user requests different ranges of the same video, it’s essential to ensure that the stored blobs don’t overlap or clash with one another. Additionally, these blobs need to be correctly combined when serving them for offline playback.

  4. Cache Management

    Developing an effective strategy for managing the cache is pivotal. Determining the duration for which cached videos should be retained, allocating an appropriate cache size, and implementing mechanisms to handle cache eviction are all crucial to preventing the cache from growing uncontrollably.

  5. IndexedDB Quotas

    Web browsers impose storage quotas on IndexedDB, setting limits on the volume of data you can store. This might necessitate the implementation of mechanisms for purging or cleaning up data to remain within these storage boundaries.

8

Thank you Gumlet community for solving my query.