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• NodeJS - efficiently and correctly convert from raw PCM to WAV at scale (without FFMPEG ?)

  13 juillet 2024, par Royi Bernthal

  I have a stream of raw PCM buffers I need to convert to playable WAV buffers.

  


  @ffmpeg.wasm can convert an individual buffer in the stream well, but it's limited to executing 1 command at a time, so it won't work in a real-life streaming scenario (streams x concurrent users). We can use it as a reference to a conversion that outputs a good playable wav.

  


  import { FFmpeg, createFFmpeg, fetchFile } from '@ffmpeg.wasm/main';

async pcmToWavFFMPEG(buffer: Buffer) {
    // bitDepth - PCM signed 16-bit little-endian
    const options = { sampleRate: '24k', channels: '1', bitDepth: 's16le' };

    this.ffmpeg.FS('writeFile', 'input.pcm', await fetchFile(buffer));

    await this.ffmpeg.run(
      '-f',
      options.bitDepth,
      '-ar',
      options.sampleRate,
      '-ac',
      options.channels,
      '-i',
      'input.pcm',
      'output.wav',
    );

    const wavBuffer = this.ffmpeg.FS('readFile', 'output.wav');

    this.ffmpeg.FS('unlink', `input.pcm`);
    this.ffmpeg.FS('unlink', `output.wav`);

    return Buffer.from(wavBuffer);
  }


  


  In order to get over the command execution limit, I've tried fluent-ffmpeg. I couldn't find a way to convert a single buffer, so I'm just passing the whole readable stream so that ffmpeg can convert all of its buffers to wav. The buffers I'm getting in on('data') aren't playable wav. The same is true for concatting the accumulated buffers in on('complete') - the result is not a playable wav.

  


  import ffmpeg from 'fluent-ffmpeg';
import internal from 'stream';

async pcmToWavFluentFFMPEG(
    readable: internal.Readable,
    callback: (chunk: Buffer) => void,
  ) {
    const options = { sampleRate: 24000, channels: 1, bitDepth: 's16le' };

    ffmpeg(readable)
      .inputFormat(options.bitDepth)
      .audioFrequency(options.sampleRate)
      .audioChannels(options.channels)
      .outputFormat('wav')
      .pipe()
      .on('data', callback);
  }


  


  I've also tried using node-wav to convert each buffer individually. It manages to convert everything to playable wavs that sound close to the desired result, however for some reason they're extremely loud and sound a bit weird.

  


  import wav from 'node-wav';

pcmToWavBad(buffer: Buffer) {
    const pcmData = new Int16Array(
      buffer.buffer,
      buffer.byteOffset,
      buffer.byteLength / Int16Array.BYTES_PER_ELEMENT,
    );

    const channelData = [pcmData]; // assuming mono channel

    return wav.encode(channelData, { sampleRate: 24000, bitDepth: 16 });
  }


  


  I've also tried wrapping the PCM as a WAV with wavefile without any actual conversion (which is redundant as PCM is contained as is in WAV), but it results in white noise :

  


  import { WaveFile } from 'wavefile';

pcmToWav(buffer: Buffer) {
    const wav = new WaveFile();

    wav.fromScratch(1, 24000, '16', buffer); // 's16le' is invalid

    return Buffer.from(wav.toBuffer());
  }


  


• FFMPEG SAR mismatch when concatenating videos

  6 septembre 2020, par marcman

  I'm trying to concatenate videos with different codecs using the concat filter. I'm also doing a bunch of processing to scale and pad the individual clips in this filter as well. However, I keep getting an error of this form :

  


  [Parsed_concat_14 @ 0x556b918ed580] Input link in1:v0 parameters (size 960x1280, SAR 0:1) do not match the corresponding output link in0:v0 parameters (1280x720, SAR 1:1)


  


  Here is my command :

  


  ffmpeg \
    -y \
    -loglevel warning \
    -stats \
    -i videos/vid0.mp4 \
    -i videos/vid1.mp4 \
    -i videos/vid2.mov \
    -filter_complex \
"[0:v]setpts=PTS-STARTPTS, scale=1920:1080, setsar=1, drawtext=expansion=strftime: basetime=$(date +%s -d'2020-07-10 16:04:44')000000 : fontcolor=white : text='%^b %d, %Y%n%l\\:%M%p' : fontsize=36 : y=1080-4*lh : x=1920-text_w-2*max_glyph_w; \
[1:v]setpts=PTS-STARTPTS, scale=810:1080, pad=width=1920:height=1080:x=555:y=0:color=black, setsar=1, drawtext=expansion=strftime: basetime=$(date +%s -d'2020-08-20 21:12:27')000000 : fontcolor=white : text='%^b %d, %Y%n%l\\:%M%p' : fontsize=36 : y=1080-4*lh : x=1365-text_w-2*max_glyph_w; \
[2:v]setpts=PTS-STARTPTS, scale=607:1080, pad=width=1920:height=1080:x=656:y=0:color=black, setsar=1, drawtext=expansion=strftime: basetime=$(date +%s -d'2020-08-27 16:42:26')000000 : fontcolor=white : text='%^b %d, %Y%n%l\\:%M%p' : fontsize=36 : y=1080-4*lh : x=1263-text_w-2*max_glyph_w; \
[0:v][0:a][1:v][1:a][2:v][2:a]concat=n=3:v=1:a=1[v][a]" \
    -map "[v]" \
    -map "[a]" \
    videos.mp4


  


  This gives the following error :

  


  [Parsed_concat_14 @ 0x563ab9d840c0] Input link in1:v0 parameters (size 960x1280, SAR 0:1) do not match the corresponding output link in0:v0 parameters (1280x720, SAR 1:1)
[Parsed_concat_14 @ 0x563ab9d840c0] Input link in2:v0 parameters (size 1080x1920, SAR 0:1) do not match the corresponding output link in0:v0 parameters (1280x720, SAR 1:1)


  


  The input videos have these resolutions :

  


  

  1. vid0.mp4 : (1280x720)

  


  2. vid1.mp4 : (960x1280)

  


  3. vid2.mp4 : (1080x1920)

  


  


  The output resolution of the concatenated output is to be 1920x1080.

  


  I've added the setsar=1 command after all my scaling and padding operations, as per this question and answer. I've also tried setdar=16/9 as in this answer, but it made no difference.

  


  What am I missing here ?

  


• What Is Ethical SEO & Why Does It Matter ?

  7 mai 2024, par Erin

  Do you want to generate more revenue ?

  Then, you need to ensure you have a steady stream of traffic flowing to your site.

  Search engines like Google, Bing and Yahoo are powerful mediums you can use to scale your business.

  Search engine optimisation (SEO) is the process of creating search engine-friendly content to draw in traffic to your website. But, if you aren’t careful, you could be crossing the line of ethical SEO into unethical SEO.

  In this article, we break down what ethical SEO is, why it’s important in business and how you can implement effective SEO into your business while remaining ethical.

  Let’s begin.

  What is ethical SEO ?

  Since the early days of the internet and search engines, business owners and marketers have tried using all kinds of SEO tactics to rank atop the search engines for relevant keywords.

  The problem ?

  Some of these practices are ethical, while others aren’t.

  What exactly is ethical SEO ?

  It’s the practice of optimising your website’s rankings in search engines by following search engine guidelines and prioritising user experience.

  

  Ethical SEO is also referred to as “white hat SEO.”

  On the other hand, businesses that break search engine rules and guidelines to “hack” their way to the top with faulty and questionable practices use unethical SEO, or “black hat SEO.”

  Ethical SEO aims to achieve higher rankings in search engines through sustainable, legitimate and fair methods.

  Black hat, or unethical SEO, aims to manipulate or “game” the system with deceptive strategies to bypass the search engine’s guidelines to rank higher.

  The two core branches of ethical SEO include :

  1. Strategies that align with search engine guidelines.
  2. Accessibility to broad audiences.

  Some examples of ethical SEO principles include :

  • Natural link building
  • Compliance with search engine guidelines
  • Establishing great user experiences
  • Creating reader-focused content

  By sticking to the right guidelines and implementing proper SEO practices, businesses can establish ethical SEO to generate more traffic and grow their brands.

  8 ethical SEO practices to implement

  If you want to grow your organic search traffic, then there’s no doubt you’ll need to have some SEO knowledge.

  While there are dozens of ways to “game” SEO, it’s best to stick to proven, ethical SEO techniques to improve your rankings.

  Stick to these best practices to increase your rankings in the search engine results pages (SERPs), increase organic traffic and improve your website conversions.

  

  1. Crafting high-quality content

  The most important piece of any ethical SEO strategy is content.

  Forget about rankings, keywords and links for a second.

  Step back and think about why people go to Google, Bing and Yahoo in the first place.

  They’re there looking for information. They have a question they need answered. That’s where you can come in and give them the answer they want. 

  How ? In the form of content.

  The best long-term ethical SEO strategy is to create the highest-quality content possible. Crafting high-quality content should be where you focus 90% of your SEO efforts.

  2. Following search engine guidelines

  Once you’ve got a solid content creation strategy, where you’re producing in-depth, quality content, you need to ensure you’re following the guidelines and rules put in place by the major search engines.

  This means you need to stay compliant with the best practices and guidelines laid out by the top search engines.

  If you fail to follow these rules, you could be penalised, your content could be downgraded or removed from search engines, and you could even have your entire website flagged, impacting your entire organic search traffic from your site.

  You need to ensure you align with the guidelines so you’re set up for long-term success with your SEO.

  3. Conducting keyword research and optimisation

  Now that we’ve covered content and guidelines, let’s talk about the technical stuff, starting with keywords.

  In the early days of SEO (late 90s), just about anyone could rank a web page high by stuffing keywords all over the page.

  While those black hat techniques used to work to “game” the system, it doesn’t work like that anymore. Google and other major search engines have much more advanced algorithms that can detect keyword stuffing and manipulation.

  Keywords are still a major part of a successful SEO strategy. You can ethically incorporate keywords into your content (and you should) if you want to rank higher. 

  Your main goal with your content is to match it with the search intent. So, incorporating keywords should come naturally throughout your content. If you try to stuff in unnecessary keywords or use spammy techniques, you may not even rank at all and could harm your website’s rankings.

  4. Incorporating natural link building

  After you’ve covered content and keywords, it’s time to dive into links. Backlinks are any links that point back to your website from another website.

  These are a crucial part of the SEO pie. Without them, it’s hard to rank high on Google. They work well because they tell Google your web page or website has authority on a subject matter.

  But you could be penalised if you try to manipulate backlinks by purchasing them or spamming them from other websites.

  Instead, you should aim to draw in natural backlinks by creating content that attracts them.

  How ? There are several options :

  • Content marketing
  • Email outreach
  • Brand mentions
  • Public relations
  • Ethical guest posting

  Get involved in other people’s communities. Get on podcasts. Write guest posts. Connect with other brands. Provide value in your niche and create content worth linking to.

  5. Respecting the intellectual property of other brands

  Content creation is moving at lightspeed in the creator economy and social media era. For better or for worse, content is going viral every day. People share content, place their spin on it, revise it, optimise it, and spread it around the internet.

  Unfortunately, this means the content is sometimes shared without the owner’s permission. Content is one form of intellectual property (IP). 

  If you share copyrighted material, you could face legal consequences.

  6. Ensuring transparency

  Transparency is one of the pillars of ethical marketing.

  If you’re running the SEO in your company or an agency, you should always explain the SEO strategies and tactics you’re implementing to your stakeholders.

  It’s best to lean on transparency and honesty to ensure your team knows you’re running operations ethically.

  7. Implementing a great user experience

  The final pillar of ethical SEO practices is offering a great user experience on your website.

  Major search engines like Google are favouring user experience more and more every year. This means knowing how to track and analyse website metrics like page load times, time on page, pageviews, media plays and event tracking.

  8. Use an ethical web analytics solution

  Last but certainly not least. Tracking your website visitors ethically is key to maintaining SEO ethics.

  You can do this by using an ethical web analytics solution like Matomo, Plausible or Fathom. All three are committed to respecting user privacy and offer ethical tracking of visitors.

  We’re a bit biassed towards Matomo, of course, but for good reasons.

  Matomo offers accurate, unsampled data along with advanced features like heatmaps, session recording, and A/B testing. These features enhance user experience and support ethical SEO practices by providing insights into user behaviour, helping optimise content. 

  Try Matomo for Free

  Get the web insights you need, without compromising data accuracy.

  Start for free

  No credit card required

  6 unethical SEO practices to avoid

  Now that we’ve covered the ethical SEO best practices let’s talk about what kind of unethical SEO practices you want to avoid.

  Remember, SEO isn’t as easy to manipulate as it once was 20 years ago.

  Algorithms are much more sophisticated now, and search engines are getting better at detecting fraudulent, scammy or unethical SEO practices every year.

  Avoid these eight unethical SEO practices to ensure you can rank high in the long term :

  

  1. Keyword stuffing

  Keyword stuffing is probably the most common unethical SEO practice. This is where someone deliberately stuffs keywords onto a page to manipulate the search engines to rank a web page higher.

  Where this is unethical isn’t always easy to detect, but in some cases, it is. It comes down to whether it’s relevant and natural or intentionally stuffing.

  2. Cloaking

  Cloaking is another unethical SEO practice where someone manipulates the information search engines see on their website.

  For example, someone may show search engines one web page on their website, but when someone clicks on it in Google, they can direct someone to a completely different page. They do this by detecting the incoming request from the user agent and presenting different content.

  3. Deceiving functionality

  Another way companies are unethically implementing SEO tactics is by deceiving people with misleading information. For example, a website may claim to provide a free resource or directory but may intentionally lead visitors to paid products.

  4. Fraudulent redirects

  Another way to deceive or mislead searchers is by creating fraudulent redirects. A redirect is a way to take someone to a different web page when they click on another one. Redirects can be useful if a page is broken or outdated. However, they can be used to deceptively take someone to a website they didn’t intend to view.

  5. Negative SEO

  Negative SEO is the intentional attempt to harm a competitor’s search engine rankings through unethical tactics.

  These tactics include duplicating their content or generating spammy links by creating low quality or irrelevant backlinks to their site.

  6. Hidden text

  Placing hidden text on a website typically has one purpose : keyword stuffing.

  Instead of making it visible to users reading the content, websites will place invisible text or text that’s hard to read on a website to try to rank the content higher and manipulate the search engines.

  3 reasons you need to implement ethical SEO

  So, why should you ensure you only implement ethical SEO in your organic traffic strategy ?

  It’s not just about what’s morally right or wrong. Implementing ethical SEO is the smartest long-term marketing strategy :

  1. Better long-term SEO

  Search engine optimisation is about implementing the “right” tactics to get your website to rank higher.

  The funny thing is many people are trying to get quick fixes by manipulating search engines to see results now.

  However, the ones who implement shady tactics and “hacks” to game the system almost always end up losing their rankings in the long term. 

  The best long-term SEO strategy is to do things ethically. Create content that helps people. Make higher quality content than your competitors. If you do those two things right, you’ll have better search traffic for years.

  2. Great brand reputation

  Not only is ethical SEO a great way to get long-term results, but it’s also a good way to maintain a solid brand reputation.

  Reputation management is a crucial aspect of SEO. All it takes is one bad incident, and your SEO could be negatively impacted.

  3. Lower chance of penalties

  If you play by the rules, you have a lower risk of being penalised by Google.

  The reality is that Google owns the search engine, not you. While we can benefit from the traffic generation of major search engines, you could lose all your rankings if you break their guidelines.

  Track SEO data ethically with Matomo

  Ethical SEO is all about :

  • Serving your audience
  • Getting better traffic in the long run

  If you fail to follow ethical SEO practices, you could be de-ranked or have your reputation on the line.

  However, if you implement ethical SEO, you could reap the rewards of a sustainable marketing strategy that helps you grow your traffic correctly and increase conversions in the long term.

  If you’re ready to start implementing ethical SEO, you need to ensure you depend on an ethical web analytics solution like Matomo.

  Unlike other web analytics solutions, Matomo prioritises user privacy, maintains transparent, ethical data collection practices, and does not sell user data to advertisers. Matomo provides 100% data ownership, ensuring that your data remains yours to own and control.

  As the leading privacy-friendly web analytics solution globally, trusted by over 1 million websites, Matomo ensures :

  • Accurate data without data sampling for confident insights and better results
  • Privacy-friendly and GDPR-compliant web analytics
  • Open-source access for transparency and creating a custom solution tailored to your needs

  Try Matomo free for 21-days. No credit card required.

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