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• Sync Audio/Video in MP4 using AutoGen FFmpeg library

  12 juillet 2016, par williamtroup

  I’m currently having problems making my audio and video streams stay synced.

  These are the AVCodecContexts I’m using :

  For Video :

  AVCodec* videoCodec = ffmpeg.avcodec_find_encoder(AVCodecID.AV_CODEC_ID_H264)
  
  AVCodecContext* videoCodecContext = ffmpeg.avcodec_alloc_context3(videoCodec);
  
  videoCodecContext->bit_rate = 400000;
  
  videoCodecContext->width = 1280;
  
  videoCodecContext->height = 720;
  
  videoCodecContext->gop_size = 12;
  
  videoCodecContext->max_b_frames = 1;
  
  videoCodecContext->pix_fmt = videoCodec->pix_fmts[0];
  
  videoCodecContext->codec_id = videoCodec->id;
  
  videoCodecContext->codec_type = videoCodec->type;
  
  videoCodecContext->time_base = new AVRational
  
  {
  
      num = 1,
  
      den = 30
  
  };

  For Audio :

  AVCodec* audioCodec = ffmpeg.avcodec_find_encoder(AVCodecID.AV_CODEC_ID_AAC)
  
  AVCodecContext* audioCodecContext = ffmpeg.avcodec_alloc_context3(audioCodec);
  
  audioCodecContext->bit_rate = 1280000;
  
  audioCodecContext->sample_rate = 48000;
  
  audioCodecContext->channels = 2;
  
  audioCodecContext->channel_layout = ffmpeg.AV_CH_LAYOUT_STEREO;
  
  audioCodecContext->frame_size = 1024;
  
  audioCodecContext->sample_fmt = audioCodec->sample_fmts[0];
  
  audioCodecContext->profile = ffmpeg.FF_PROFILE_AAC_LOW;
  
  audioCodecContext->codec_id = audioCodec->id;
  
  audioCodecContext->codec_type = audioCodec->type;

  When writing the video frames, I setup the PTS position as follows :

  outputFrame->pts = frameIndex;  // The current index of the image frame being written

  I then encode the frame using avcodec_encode_video2(). After this, I call the following to setup the time stamps :

  ffmpeg.av_packet_rescale_ts(&packet, videoCodecContext->time_base, videoStream->time_base);

  This plays perfectly.

  However, when I do the same for audio, the video plays in slow motion, plays the audio first and then carry’s on with the video afterwards with no sound.

  I cannot find an example anywhere of how to set pts/dts positions for video/audio in an MP4 file. Any examples of help would be great !

  Also, I’m writing the video frames first, after which (once they are all written) I write the audio. I’ve updated this question with the adjusted values suggested in the comments.

  I’ve uploaded a test video to show my results here : http://www.filedropper.com/test_124

• C++ h264 ffmpeg/libav encode/decode(lossless) issues

  1er février 2017, par MrSmith

  Insights to encode/decode video with ffmpeg h264 (lossless)

  So I got something working on the encoding part, encode an avi in 264 however VLC wont play it, however Totem will.
  Decoding the same file proves troublesome. (I want the exact same data/frame going in as going out), I get these ;

  saving frame   5
  
  Video decoding
  
  [h264 @ 0x1d19880] decode_slice_header error
  
  frame :6
  
  saving frame   6
  
  Video decoding
  
  [h264 @ 0x1d19880] error while decoding MB 15 7, bytestream -27
  
  [h264 @ 0x1d19880] concealing 194 DC, 194 AC, 194 MV errors in I frame
  
  frame :7
  
  saving frame   7
  
  Video decoding
  
  [h264 @ 0x1d19880] decode_slice_header error

  and ultimatly this

  [H264 Decoder @ 0x7f1320766040] frame :11
  
  Broken frame packetizing
  
  [h264 @ 0x1d19880] SPS changed in the middle of the frame
  
  [h264 @ 0x1d19880] decode_slice_header error
  
  [h264 @ 0x1d19880] no frame!
  
  Error while decoding frame 11

  GAME OVER.

  Now I suspect that I have to go back to 1. the encoding part, there is problary a good reason VLC wont play it !

  I encode like this.

  void encode(char *Y,char *U,char *V){
  
  av_init_packet(&pkt);
  
  pkt.data = NULL;    // packet data will be allocated by the encoder
  
  pkt.size = 0;
  
  fflush(stdout);
  
  
  
  frame->data[0] = (uint8_t*)Y;
  
  frame->data[1] = (uint8_t*)U;
  
  frame->data[2] = (uint8_t*)V;
  
  frame->pts = ++i;
  
  
  
  ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
  
  if (ret < 0) {
  
      fprintf(stderr, "Error encoding frame\n");
  
      exit (EXIT_FAILURE);
  
  }
  
  if (got_output) {
  
      printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
      fwrite(pkt.data, 1, pkt.size, f);
  
      av_free_packet(&pkt);
  
  }
  
  }

  And the codec is setup like this :

  AVCodecID dasd = AV_CODEC_ID_H264;
  
  codec = avcodec_find_encoder(dasd);
  
  c = avcodec_alloc_context3(codec);
  
  c->bit_rate = 400000;
  
  c->width = 320;
  
  c->height = 240;
  
  c->time_base= (AVRational){1,25};
  
  c->gop_size = 10; 
  
  c->max_b_frames=1;
  
  c->pix_fmt = AV_PIX_FMT_YUV420P;
  
  av_opt_set(c->priv_data, "preset", "slow", 0);
  
  avcodec_open2(c, codec, NULL);

  Since I am going for lossless i am not dealing with delayed frames(is this a correct assumption ?)
  I may not actually be encoding lossless, it seems like I may have to go with something like

  AVDictionary *param;
  
  av_dict_set(&param, "qp", "0", 0);

  And then open...

  So I guess me questions is these :

  • What are the correct codec params for lossless encoding (and advice if h264 is a terrible idea in this regard).
  • Do I need to handle delayed frames when going for lossless ?
  • Why is VLC mad at me ?

  Thanks.

• Conversion Rate Optimisation Statistics for 2024 and Beyond

  21 novembre 2023, par Erin — Analytics Tips

  Driving traffic to your website is only half the battle. The real challenge — once you’ve used a web analytics solution to understand how users behave — is turning more of those visitors into customers.

  That doesn’t happen by accident. You need to employ conversion rate optimisation strategies and tools to see even a small lift in conversion rates. The good news is that it doesn’t take much to see massive results. Raising your conversion rate from 1% to 3% can triple your revenue. 

  In even better news, you don’t have to guess at the best ways to improve your conversion rate. We’ve done the hard work and collected the most recent and relevant conversion rate optimisation statistics to help you. 

  General conversion rate optimisation statistics

  It appears the popularity of conversion rate optimisation is soaring. According to data collected by Google Trends, there were more people searching for the term “conversion rate optimization” in September 2023 than ever before. 

  As you can see from the chart below, the term’s popularity is on a clear upward trajectory, meaning even more people could be searching for it in the near future. (Source)

  

  Do you want to know what the average landing page conversion rate is ? According to research by WordStream, the average website conversion rate across all industries is 2.35%. 

  That doesn’t paint the whole picture, however. Better-performing websites have significantly higher conversion rates. The top 25% of websites across all industries convert at a rate of 5.31% or higher. (Source)

  Let’s break things down by industry now. The Unbounce Conversion Benchmark Report offers a detailed analysis of how landing pages convert across various industries.

  First, we have the Finance and Insurance industry, which boasts a conversion rate of 15.6%. 

  On the other end, agencies appears to be one of the worst-performing. Agencies’ landing pages convert at a rate of 8.8%. (Source)

  

  What about the size of the conversion rate optimisation industry ? Given the growth in popularity of the term in Google, surely the industry is experiencing growth, right ?

  You’d be correct in that assumption. The conversion rate optimisation software market was valued at $771.2 million in 2018 and is projected to reach $1.932 billion by 2026 — a compound annual growth rate (CAGR) of 9.6%.

  Statistics on the importance of conversion rate optimisation

  If you’re reading this article, you probably think conversion rate optimisation is pretty important. But do you know its importance and where it ranks in your competitors’ priorities ? Read on to find out. 

  Bounce rate — the number of people who leave your website without visiting another page or taking action — is the scourge of conversion rate optimisation efforts. Every time someone bounces from your site, you lose the chance to convert them.

  The questions, then, are : how often do people bounce on average and how does your bounce rate compare ? 

  Siege Media analysed over 1.3 billion sessions from a range of traffic sources, including 700 million bounces, to calculate an average bounce rate of 50.9%. (Source)

  

  Bounce rates vary massively from website to website and industry to industry, however. Siege Media’s study unveils an array of average bounce rates across industries :

  • Travel – 82.58%
  • B2B – 65.17%
  • Lifestyle – 64.26%
  • Business and Finance – 63.51%
  • Healthcare – 59.50%
  • eCommerce – 54.54%
  • Insurance – 45.96%
  • Real Estate – 40.78%

  It won’t come as much of a surprise to learn that marketers are determined to reduce bounce rates and improve lead conversion. Today’s marketers are highly performance-based. When asked about their priorities for the coming year, 79% of marketers said their priority was generating quality qualified leads — the most popular answer in the survey. (Source)

  Just because it is a priority for marketers doesn’t mean that everyone has their stuff together. If you have a conversion rate optimisation process in place, you’re in the minority. According to research by HubSpot, less than one in five marketers (17%) use landing page A/B tests to improve their conversion rates. (Source)

  When it comes to personalisation strategies – a common and effective tool to increase conversion rates — the picture isn’t any rosier. Research by Salesforce found just over one-quarter of markets are confident their organisation has a successful strategy for personalisation. (Source)

  Conversion rate optimisation tactics statistics

  There are hundreds of ways to improve your website’s conversion rates. From changing the color of buttons to the structure of your landing page to your entire conversion funnel, in this section, we’ll look at the most important statistics you need to know when choosing tactics and building your own CRO experiments. 

  If you are looking for the best method to convert visitors, then email lead generation forms are the way to go, according to HubSpot. This inoffensive and low-barrier data collection method boasts a 15% conversion rate, according to the marketing automation company’s research. (Source)

  Where possible, make your call-to-actions personalised. Marketing personalisation, whether through behavioral segmentation or another strategy, is an incredibly powerful way of showing users that you care about their specific needs. It’s no great surprise, then, that HubSpot found personalised calls-to-actions perform a whopping 202% better than basic CTAs. (Source)

  If you want to boost conversion rates, then it’s just as important to focus on quantity as well as quality. Yes, a great-looking, well-written landing page will go a long way to improving your conversion rate, but having a dozen of these pages will do even more. 

  Research by HubSpot found companies see a 55% increase in leads when they increase the number of landing pages from 10 to 15. What’s more, companies with over 40 landing pages increase conversion by more than 500%. (Source)

  

  User-generated content (UGC) should also be high on your priority list to boost conversion rates. Several statistics show how powerful, impactful and persuasive social proof like user reviews can be. 

  Research shows that visitors who scroll to the point where they encounter user-generated content increase the likelihood they convert by a staggering 102.4%. (Source)

  Other trust signs can be just as impactful. Research by Trustpilot found that the following four trust signals make consumers more likely to make a purchase when shown on a product page :

  • Positive star rating and reviews (85% more likely to make a purchase)
  • Positive star rating (78%)
  • Positive customer testimonials (82%)
  • Approved or authorised seller badge (76%)

  (Source)

  Showing ratings and reviews has also increased conversion rates by 38% on home appliances and electronics stores. (Source)

  And no wonder, given that consumers are more likely to buy from brands they trust than brands they love, according to the 2021 Edelman Trust Barometer Special Report. (Source) 

  A lack of trust is also one of the top four reasons consumers abandon their shopping cart at checkout. (Source) 

  Traffic source conversion rate statistics

  What type of traffic works the best when it comes to conversions, or how often you should be signing up users to your mailing list ? Let’s look at the stats to find out. 

  Email opt-ins are one of the most popular methods for collecting customer information — and an area where digital marketers spend a lot of time and effort when it comes to conversion rate optimisation. So, what is the average conversion rate of an email opt-in box ?

  According to research by Sumo — based on 3.2 billion users who have seen their opt-in boxes — the average email opt-in rate is 1.95%. (Source)

  Search advertising is an effective way of driving website traffic, but how often do those users click on these ads ?

  WordStream’s research puts the average conversion of search advertising for all industries at 6.11%. (Source)

  The arts and entertainment industry enjoys the highest clickthrough rates (11.78%), followed by sports and recreation (10.53%) and travel (10.03%). Legal services and the home improvement industry have the lowest clickthrough rates at 4.76% and 4.8%, respectively.

  

  If you’re spending money on Google ads, then you’d better hope a significant amount of users convert after clicking them. 

  Unfortunately, conversion rates from Google ads decreased year-on-year for most industries in 2023, according to research by WordStream — in some cases, those decreases were significant. The only two industries that didn’t see a decrease in conversion rates were beauty and personal care and education and instruction. (Source)

  The average conversion rate for search ads across all industries is 7.04%. The animal and pet niche has the highest conversion rate (13.41%), while apparel, fashion and jewelry have the lowest conversion rate (1.57%). (Source)

  What about other forms of traffic ? Well, there’s good reason to try running interstitial ads on smartphone apps if you aren’t already. Ads on the iOS app see a 14.3 percent conversion rate on average. (Source)

  E-commerce conversion rate optimisation statistics (400 words)

  Conversion rate optimisation can be the difference between a store that sets new annual sales records and one struggling to get by. 

  The good news is that the conversion rate among US shoppers was the highest it’s ever been in 2021, with users converting at 2.6%. (Source)

  If you have a Shopify store, then you may find conversion rates a little lower. A survey by Littledata found the average conversion rate for Shopify was 1.4% in September 2022. (Source)

  What about specific e-commerce categories ? According to data provided by Dynamic Yield, the consumer goods category converted at the highest rate in September 2023 (4.22%), a spike of 0.34% from August. 

  Generally, the food and beverage niche boasts the highest conversion rate (4.87%), and the home and furniture niche has the lowest conversion rate (1.44%). (Source)

  If you’re serious about driving sales, don’t focus on mobile devices at the expense of consumers who shop on desktop devices. The conversion rate among US shoppers tends to be higher for desktop users than for mobile users. 

  

  In the second quarter of 2022, for instance, desktop shoppers converted at a rate of 3% on average compared to smartphone users who converted at an average rate of 2%. (Source)

  Increase your conversions with Matomo

  Conversion rate optimisation can help you grow your subscriber list, build your customer base and increase your revenue. Now, it’s time to put what you’ve learned into practice.

  Use the advice above to guide your experiments and track everything with Matomo. Achieve unparalleled data accuracy while harnessing an all-in-one solution packed with essential conversion optimisation features, including Heatmaps, Session Recordings and A/B Testing. Matomo makes it easier than ever to analyse conversion-focused experiments.

  Get more from your conversion rate optimisations by trying Matomo free for 21 days. No credit card required.