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MediaSPIP 0.1 Beta version
25 avril 2011, parMediaSPIP 0.1 beta is the first version of MediaSPIP proclaimed as "usable".
The zip file provided here only contains the sources of MediaSPIP in its standalone version.
To get a working installation, you must manually install all-software dependencies on the server.
If you want to use this archive for an installation in "farm mode", you will also need to proceed to other manual (...) -
Multilang : améliorer l’interface pour les blocs multilingues
18 février 2011, parMultilang est un plugin supplémentaire qui n’est pas activé par défaut lors de l’initialisation de MediaSPIP.
Après son activation, une préconfiguration est mise en place automatiquement par MediaSPIP init permettant à la nouvelle fonctionnalité d’être automatiquement opérationnelle. Il n’est donc pas obligatoire de passer par une étape de configuration pour cela. -
Le profil des utilisateurs
12 avril 2011, parChaque utilisateur dispose d’une page de profil lui permettant de modifier ses informations personnelle. Dans le menu de haut de page par défaut, un élément de menu est automatiquement créé à l’initialisation de MediaSPIP, visible uniquement si le visiteur est identifié sur le site.
L’utilisateur a accès à la modification de profil depuis sa page auteur, un lien dans la navigation "Modifier votre profil" est (...)
Sur d’autres sites (14207)
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Accessibility Testing : Why It Matters and How to Get Started
7 mai 2024, par ErinNearly 96% of website homepages had failures with meeting web accessibility criteria in 2024. Aside from not complying with web accessibility laws and regulations, companies are failing a growing number of users with accessibility needs.
With disabilities, chronic illnesses and ageing populations all rising, brands need to take accessibility more seriously.
In this article, we explain why accessibility testing is so important and how you can get started today.
What is accessibility testing ?
Accessibility testing optimises digital experiences to make them accessible for users with a range of disabilities and impairments. This includes users with vision impairments, hearing loss, neurodivergence, motor disabilities and cognitive conditions.
The goal is to create inclusive experiences for everyone by implementing UX principles that address the usability needs of diverse audiences.
To help developers create accessible experiences, the World Wide Web Consortium (W3C) created the Web Content Accessibility Guidelines (WCAG). The international WCAG standards define the Four Principles of Accessibility :
- Perceivable : Information and user interface components must be presentable to users in ways they perceive.
- Operable : User interface components and navigation must be operable.
- Understandable : Information and the operation of user interfaces must be understandable.
- Robust : Content must be robust enough to be interpreted reliably by various user agents, including assistive technologies.
The current version of WCAG (2.2) contains 86 success criteria with three grades representing conformance levels :
- Level A is the minimum conformance rating, indicating that web content is accessible to most users.
- Level AA is the recommended conformance level to make content accessible to almost everyone, including users with severe disabilities.
- Level AAA is the highest conformance rating, making content accessible to everyone, regardless of disability.
Why is accessibility testing important ?
With record numbers of lawsuits over online accessibility cases, it’s clear that companies underestimate the importance of accessibility testing. Here are seven key reasons you should pay more attention to it :
- Create inclusive experiences : Above all, accessibility testing creates inclusive experiences for all users.
- Adhere to accessibility regulations : Accessibility laws in most major markets — including the EU web accessibility policy — make it illegal for companies to discriminate against users with disabilities.
- Social responsibility : Companies have an ethical responsibility to cater to all users and consumers. 57% say they’re more loyal to brands that commit to addressing social inequities.
- Accessibility needs are growing : 16% of the world’s population (1 in 6) experience significant disability and the number will continue to grow as ageing populations rise.
- Improve experiences for everyone : Accessibility improves experiences for all users — for example, 80% of UK viewers aged 18-25 (2021) watch content with subtitles enabled.
- Maximise marketing reach : Platforms like Google prioritise accessibility yearly, making accessible content and experiences more visible.
- Accessibility is profitable : Inclusive companies earn 1.6x more revenue, 2.6x more net income and 2x more profit, according to Accenture (PDF).
Who needs inclusive UX ?
Accessibility testing starts with understanding the usability needs of audiences with disabilities and impairments. Here’s a quick summary of the most common impairments and some of the needs they have in common :
- Visual impairments : Users may rely on screen readers, magnification software, braille displays, etc. or require certain levels of contrast, text sizes and colour combinations to aid visibility.
- Hearing impairments : Users may rely on closed captions and subtitles for video content, transcripts for multimedia content and visual alerts/notifications for updates.
- Motor or mobility impairments : Users might rely on adaptive keyboards, voice recognition and other assistive devices.
- Cognitive and neurological impairments : Users may rely on technologies like text-to-speech software or require simplified user interfaces, contrast designs, etc., to aid comprehension.
- Speech impairments : Users may rely on speech recognition and dictation software for any interaction that requires them to speak (e.g., automated customer service machines).
While accessibility tools can alleviate certain accessibility challenges, inclusive design can remove much of the burden from users. This can involve using plenty of contrast, careful font selection, increasing whitespace and plenty of other design choices.
Refer to the latest version of the WCAG for further guidance.
How to run accessibility testing
Now that we’ve emphasised the importance of accessibility, let’s explain how you can implement your own accessibility testing strategy.
Create your accessibility testing plan
Careful planning is crucial for making accessibility testing affordable and profitable. This starts with identifying the assets you need to test and optimise. This may include :
- Website or web app
- Mobile app
- Videos
- Podcasts and audio
- PDFs
- Marketing emails
Map out all the assets your target audience interacts with and bring them into your accessibility testing plan. Optimising your website for screen readers is great, but you don’t want to forget your marketing emails and exclude vision-impaired users.
Once you’ve got a complete list of assets, identify the elements and interactions with each one that require accessibility testing. For example, on your website, you should optimise navigation, user interfaces, layouts, web forms, etc.
You also need to consider the impact of device types. For example, how touchscreens change the experience for motor impairments.
Now that you know the scope of your testing strategy, it’s time to define your accessibility standards. Use external frameworks like WCAG guidelines and relevant legal requirements to create an internal set of standards.
Once your accessibility standards are complete, train your staff at every level. This includes designers, developers, and content creators — everyone who works on assets is included in your accessibility testing strategy.
Implement your accessibility standards throughout the design and development phases. Aim to create the most inclusive experiences possible before the accessibility testing stage.
Implement accessibility practices at every level
Treating accessibility as an afterthought is the biggest mistake you can make. Aside from neglecting the importance of accessibility, it’s simply not affordable to create assets and then optimise them for accessibility.
Instead, you need to implement accessibility standards in every design and development stage. This way, you create inclusive assets from the beginning, and accessibility testing flags minor fixes rather than overhauls.
By extension, you can take lessons from accessibility tests and update your accessibility standards to improve the quality of future assets.
Set clear specifications in your accessibility standards for everyone to follow. For example, content publishers should be responsible for adding alt-text to all images. Make designers responsible for following contrast guidelines when optimising elements like CTA buttons.
Next, managers can review assets and check for accessibility standards before anything is signed off. This way, you achieve higher test accessibility scores, and most fixes should be minor.
This is the key to making accessibility testing manageable and profitable.
Automate accessibility testing
Automation is the other big factor in making accessibility efficient. With the right tools, you can run tests periodically without any manual workload, collecting data and flagging potential issues at almost no cost.
For example, you can run automated accessibility tests on your website every month to check for common issues. This might flag up pages without alt-text for images, colour issues on a new batch of landing pages or a sudden drop in mobile loading times.
Every automated test you can run reduces the manual workload of optimising accessibility. This frees up more time for the manual tests that require the attention of accessibility experts.
- Free up time for accessibility tasks that require manual testing
- Identify issues with new content, assets, code, etc. faster
- Run automated accessibility testing on new CRO changes
Schedule manual accessibility reviews
While it’s important to automate as much accessibility testing as possible, most accessibility standards require some form of manual testing. If we use the WCAG standards as a guideline, more than 70% of success require manual review and verification, including :
- Testing websites with a screen reader
- Navigating apps by only using a keyword
- Quality assessing closed captions and subtitles
- Testing web forms for people using speech input
- Checking conversion actions for users with mobility issues (CTAs, forms, payments, etc.)
Yes, you can automatically check all images for alt-text, but simply providing alt-text isn’t enough. You also have to review alt-text to make sure they’re descriptive, accurate and informative about the experience.
Once again, the best way to minimise your time spent on manual testing is to implement accessibility standards throughout design and development. Train your content publishers to create alt-text that meets your criteria and editors to review them before pieces are signed off.
This way, you should always have the required alt-text before the content reaches the accessibility testing stage. The same applies to video transcriptions, web forms, website navigation, etc.
Building a culture of accessibility makes the testing process as efficient as possible.
What tools do you need for accessibility testing ?
Now that we’ve covered the key essentials of accessibility testing, let’s look at some of the best accessibility testing tools to help you implement your strategy.
accessiBe : AI-powered accessibility testing automation
accessiBe is an accessibility testing automation and management system. It incorporates two core products : accessWidget for automating UI accessibility and accessFlow as an all-in-one solution for developers.
Key features :
- Automated accessibility testing
- Accessibility widget for easy optimisation
- Product accessibility for web, mobile and native apps
- AI-powered accessibility insights
- Compliance with WCAG, EAA and more
As explained earlier, automation is crucial for making accessibility testing efficient and profitable. With accessiBe, you can automate the first line of accessibility checks so testers only need to get involved when manual action is necessary.
Maze : Intelligent usability testing software
Maze is a usability testing system that uses AI and automation to enhance traditional qualitative testing. You can run automated tests on live websites, capture survey feedback and recruit users to test experiences with real people.
Key features :
- Live website testing
- Feedback surveys
- Usability interviews
- Test recruitment
- Automated analysis
While traditional usability interviews can provide in-depth insights, they’re expensive, time-consuming and difficult to run at scale. Maze’s solution is a hybrid testing system that automates data capture and analysis while supporting real user testing in one system.
Matomo : Empowering people with ethical web analytics
Matomo is a web analytics solution that gives you 100% data ownership while respecting user privacy. Think of this as a Google Analytics alternative that doesn’t use your visitors’ data for advertising purposes.
Key features :
- Privacy-friendly and GDPR-compliant tracking
- Conversion rate optimisation features like heatmaps, session recordings, A/B testing and more
- Accurate, unsampled data – see 40-60% more data than other analytics tools that sample data
- Open-source
Accessibility starts with creating quality experiences for everyone. Matomo reliably captures 100% of the data you need to optimise experiences without losing their trust. Instead of handing their personal info to Google or other tech giants, you retain full data ownership — fully compliant with GDPR, CCPA, etc.
Try Matomo free for 21-days (no credit card required), or speak to our sales team for more info on how Matomo can enhance your site’s user experience and support your accessibility testing strategy.
Try Matomo for Free
Get the web insights you need, without compromising data accuracy.
UserTesting : Video-based user testing software
UserTesting is the more traditional system for running usability tests with real people. The platform helps you recruit users and manage usability tests with a series of sessions and video interviews.
Key features :
- Usability testing
- Test recruitment
- Live interviews
- AI-powered insights
- Usability services
UserTesting is a slower, more expensive approach to testing experiences, but its video-based interviews allow you to have meaningful conversations with real users.
Siteimprove : WCAG compliance testing
Siteimprove automates website testing, accessibility and optimisation. It includes dedicated tools for checking WCAG and DCI compliance with an automated scoring system. This helps you keep track of scores and identify any accessibility and usability issues faster.
Key features :
- Automated accessibility checks
- Inclusivity scores
- Accessibility recommendations
- Accessibility tracking
- Marketing and revenue attribution
- Usability insights
Siteimprove provides a first line of accessibility testing with automated checks and practical recommendations. It also tracks accessibility scores, including ratings for all three WCAG compliance levels (A, AA and AAA).
Find the value in accessibility testing
Accessibility testing isn’t only a moral obligation ; it’s good business. Aside from avoiding fines and lawsuits, inclusive experiences are increasingly profitable. User bases with accessibility needs are only growing while non-disabled audiences are using accessibility resources like subtitles and transcripts in greater numbers.
Accessibility improves everyone’s experiences, and this only does good things for conversion rates, revenue and profit.
Start building your datasets for accessibility testing today with a Matomo 21-day free trial — no credit card required. Gain 100% ownership over your analytics data while complying with GDPR and other data privacy regulations.
Try Matomo for Free
21 day free trial. No credit card required.
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What Are Website KPIs (10 KPIs and Best Ways to Track Them)
3 mai 2024, par ErinTrying to improve your website’s performance ?
Have you ever heard the phrase, “What gets measured gets managed ?”
To improve, you need to start crunching your numbers.
The question is, what numbers are you supposed to track ?
If you want to improve your conversions, then you need to track your website KPIs.
In this guide, we’ll break down the top website KPIs you need to be tracking and how you can track them so you can double down on what’s working with your website (and ditch what’s not).
Let’s begin.
What are website KPIs ?
Before we dive into website KPIs, let’s define “KPI.”
A KPI is a key performance indicator.
You can use this measurable metric to track progress toward a specific objective.
A website KPI is a metric to track progress towards a specific website performance objective.
Website KPIs help your business identify strengths and weaknesses on your website, activities you’re doing well (and those you’re struggling with).
Web KPIs can give you and your team a target to reach with simple checkpoints to show you whether you’re on the right track toward your goals.
By tracking website KPIs regularly, you can ensure your organisation performs consistently at a high level.
Whether you’re looking to improve your traffic, leads or revenue, keeping a close eye on your website KPIs can help you reach your goals.
10 Website KPIs to track
If you want to improve your site’s performance, you need to track the right KPIs.
While there are plenty of web analytics solutions on the market today, below we’ll cover KPIs that are automatically tracked in Matomo (and don’t require any configuration).
Here are the top 10 website KPIs you need to track to improve site performance and grow your brand :
1. Pageviews
Website pageviews are one of the most important KPIs to track.
What is it exactly ?
It’s simply the number of times a specific web page has been viewed on your site in a specific time period.
For example, your homepage might have had 327 pageviews last month, and only 252 this month.
This is a drop of 23%.
A drop in pageviews could mean your search engine optimisation or traffic campaigns are weakening. Alternatively, if you see pageviews rise, it could mean your marketing initiatives are performing well.
High or low pageviews could also indicate potential issues on specific pages. For example, your visitors might have trouble finding specific pages if you have poor website structure.
2. Average time on page
Now that you understand pageviews, let’s talk about average time on page.
This is simple : it’s the average amount of time your visitors spend on a particular web page on your site.
This isn’t the average time they spend on your website but on a specific page.
If you’re finding that you’re getting steady traffic to a specific web page, but the average time on the page is low, it may mean the content on the page needs to be updated or optimised.
Tracking your average time on page is important, as the longer someone stays on a page, the better the experience.
This isn’t a hard and fast rule, though. For specific types of content like knowledge base articles, you may want a shorter period of time on page to ensure someone gets their answer quickly.
3. Bounce rate
Bounce rate sounds fun, right ?
Well, it’s not usually a good thing for your website.
A bounce rate is how many users entered your website but “bounced” away without clicking through to another page.
Your bounce rate is a key KPI that helps you determine the quality of your content and the user experience on individual pages.
You could be getting plenty of traffic to your site, but if the majority are bouncing out before heading to new pages, it could mean that your content isn’t engaging enough for your visitors.
Remember, like average time on page, your bounce rate isn’t a black-and-white KPI.
A higher bounce rate may mean your site visitors got exactly what they needed and are pleased.
But, if you have a high bounce rate on a product page or a landing page, that is a sign you need to optimise the page.
4. Exit rate
Bounce rate is the percentage of people who left the website after visiting one page.
Exit rate, on the other hand, is the percentage of website visits that ended on a specific page.
For example, you may find that a blog post you wrote has a 19% exit rate and received 1,000 visits that month. This means out of the 1,000 people who viewed this page, 190 exited after visiting it.
On the other hand, you may find that a second blog post has 1,000 pageviews, but a 10% exit rate, with only 100 people leaving the site after visiting this page.
What could this mean ?
This means the second page did a better job keeping the person on your website longer. This could be because :
- It had more engaging content, keeping the visitors’ interest high
- It had better internal links to other relevant pieces of content
- It had a better call to action, taking someone to another web page
If you’re an e-commerce store and notice that your exit rate is higher on your product, cart or checkout pages, you may need to adjust those pages for better conversions.
5. Average page load time
Want to know another reason you may have a high exit rate or bounce rate on a page ?
Your page load time.
The average page load time is the average time it takes (in seconds) from the moment you click through to a page until it has fully rendered within your browser.
In other words, it’s the time it takes after you click on a page for it to be fully functional.
Your average load time is a crucial website KPI because it significantly impacts page performance and the user experience.
How important is your page load time ?
Nearly 53% of website visitors expect e-commerce pages to load in 3 seconds or less.
You will likely lose visitors if your pages take too long to load.
You could have the best content on a web page, but if it takes too long to load, your visitors will bounce, exit, or simply be frustrated.
6. Conversions
Conversions.
It’s one of the most popular words in digital marketing circles.
But what does it mean ?
A conversion is simply the number of times someone takes a specific action on your website.
For example, it could be wanting someone to :
- Read a blog post
- Click an external link
- Download a PDF guide
- Sign up to your email list
- Comment on your blog post
- Watch a new video you uploaded
- Purchase a limited-edition product
- Sign up for a free trial of your software
To start tracking conversions, you need to first decide what your business goals are for your website.
With Matomo, you can set up conversions easily through the Goals feature. Simply set up your website goals, and Matomo will automatically track the conversions towards that objective (as a goal completion).
Simply choose what conversion you want to track, and you can analyse when conversions occur through the Matomo platform.
7. Conversion rate
Now that you know what a conversion is, it’s time to talk about conversion rate.
This key website KPI will help you analyse your performance towards your goals.
Conversion rate is simply the percentage of visitors who take a desired action, like completing a purchase, signing up for a newsletter, or filling out a form, out of the total number of visitors to your website or landing page.
Understanding this percentage can help you plan your marketing strategy to improve your website and business performance.
For instance, let’s say that 2% of your website visitors purchase a product on your digital storefront.
Knowing this, you could tweak different levers to increase your sales.
If your average order value is $50 and you get 100,000 visits monthly, you make about $100,000.
Let’s say you want to increase your revenue.
One option is to increase your traffic by implementing campaigns to increase different traffic sources, such as social media ads, search ads, organic social traffic, and SEO.
If you can get your traffic to 120,000 visitors monthly, you can increase your revenue to $120,000 — an additional $20,000 monthly for the extra 20,000 visits.
Or, if you wanted to increase revenue, you could ignore traffic growth and simply improve your website with conversion rate optimisation (CRO).
CRO is the practice of making changes to your website or landing page to encourage more visitors to take the desired action.
If you can get your conversion rate up to 2.5%, the calculation looks like this :
100,000 visits x $50 average order value x 2.5% = $125,000/month.
8. Average time spent on forms
If you want more conversions, you need to analyse forms.
Why ?
Form analysis is crucial because it helps you pinpoint where users might be facing obstacles.
By identifying these pain points, you can refine the form’s layout and fields to enhance the user experience, leading to higher conversion rates.
In particular, you should track the average time spent on your forms to understand which ones might be causing frustration or confusion.
The average time a visitor spends on a form is calculated by measuring the duration between their first interaction with a form field (such as when they focus on it) and their final interaction.
Find out how Concrete CMS tripled their leads using Form Analytics.
9. Play rate
One often overlooked website KPI you need to be tracking is play rate.
What is it exactly ?
The percentage of visitors who click “play” on a video or audio media format on a specific web page.
For example, if you have a video on your homepage, and 50 people watched it out of the 1,000 people who visited your website today, you have a play rate of 5%.
Play rate lets you track whenever someone consumes a particular piece of audio or video content on your website, like a video, podcast, or audiobook.
Not all web analytics solutions offer media analytics. However, Matomo lets you track your media like audio and video without the need for configuration, saving you time and upkeep.
10. Actions per visit
Another crucial website KPI is actions per visit.
This is the average number of interactions a visitor has with your website during a single visit.
For example, someone may visit your website, resulting in a variety of actions :
- Downloading content
- Clicking external links
- Visiting a number of pages
- Conducting specific site searches
Actions per visit is a core KPI that indicates how engaging your website and content are.
The higher the actions per visit, the more engaged your visitors typically are, which can help them stay longer and eventually convert to paying customers.
Track your website KPIs with Matomo today
Running a website is no easy task.
There are dozens of factors to consider and manage :
- Copy
- Design
- Performance
- Tech integrations
- And more
But, to improve your website and grow your business, you must also dive into your web analytics by tracking key website KPIs.
Managing these metrics can be challenging, but Matomo simplifies the process by consolidating all your core KPIs into one easy-to-use platform.
As a privacy-friendly and GDPR-compliant web analytics solution, Matomo tracks 20-40% more data than other solutions. So you gain access to 100% accurate, unsampled insights, enabling confident decision-making.
Join over 1 million websites that trust Matomo as their web analytics solution. Try it free for 21 days — no credit card required.
Try Matomo for Free
21 day free trial. No credit card required.
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FFmpeg C++ API : Using HW acceleration (VAAPI) to transcode video coming from a webcam
17 avril 2024, par nicohI'm actually trying to use HW acceleration with the FFmpeg C++ API in order to transcode the video coming from a webcam (which may vary from one config to another) into a given output format (i.e : converting the video stream coming from the webcam in MJPEG to H264 so that it can be written into a MP4 file).


I already succeeded to achieve this by transferring the AVFrame output by the HW decoder from GPU to CPU, then transfer this to the HW encoder input (so from CPU to GPU).
This is not so optimized and on top of that, for the given above config (MJPEG => H264), I cannot provide the output of the decoder as an input for the encoder as the MJPEG HW decoder wants to output in RGBA pixel format, and the H264 encoder wants NV12. So I have to perform pixel format conversion on CPU side.


That's why I would like to connect the output of the HW video decoder directly to the input of the HW encoder (inside the GPU).
To do this, I followed this example given by FFmpeg : https://github.com/FFmpeg/FFmpeg/blob/master/doc/examples/vaapi_transcode.c.


This works fine when transcoding an AVI file with MJPEG inside to H264 but it fails when using a MJPEG stream coming from a webcam as input.
In this case, the encoder says :


[h264_vaapi @ 0x5555555e5140] No usable encoding profile found.


Below the code of the FFmpeg example I modified to connect on webcam instead of opening input file :


/*
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

/**
 * @file Intel VAAPI-accelerated transcoding API usage example
 * @example vaapi_transcode.c
 *
 * Perform VAAPI-accelerated transcoding.
 * Usage: vaapi_transcode input_stream codec output_stream
 * e.g: - vaapi_transcode input.mp4 h264_vaapi output_h264.mp4
 * - vaapi_transcode input.mp4 vp9_vaapi output_vp9.ivf
 */

#include 
#include 
#include <iostream>

//#define USE_INPUT_FILE

extern "C"{
#include <libavutil></libavutil>hwcontext.h>
#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libavdevice></libavdevice>avdevice.h>
}

static AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
static AVBufferRef *hw_device_ctx = NULL;
static AVCodecContext *decoder_ctx = NULL, *encoder_ctx = NULL;
static int video_stream = -1;
static AVStream *ost;
static int initialized = 0;

static enum AVPixelFormat get_vaapi_format(AVCodecContext *ctx,
 const enum AVPixelFormat *pix_fmts)
{
 const enum AVPixelFormat *p;

 for (p = pix_fmts; *p != AV_PIX_FMT_NONE; p++) {
 if (*p == AV_PIX_FMT_VAAPI)
 return *p;
 }

 std::cout << "Unable to decode this file using VA-API." << std::endl;
 return AV_PIX_FMT_NONE;
}

static int open_input_file(const char *filename)
{
 int ret;
 AVCodec *decoder = NULL;
 AVStream *video = NULL;
 AVDictionary *pInputOptions = nullptr;

#ifdef USE_INPUT_FILE
 if ((ret = avformat_open_input(&ifmt_ctx, filename, NULL, NULL)) < 0) {
 char errMsg[1024] = {0};
 std::cout << "Cannot open input file '" << filename << "', Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 return ret;
 }
#else
 avdevice_register_all();
 av_dict_set(&pInputOptions, "input_format", "mjpeg", 0);
 av_dict_set(&pInputOptions, "framerate", "30", 0);
 av_dict_set(&pInputOptions, "video_size", "640x480", 0);

 if ((ret = avformat_open_input(&ifmt_ctx, "/dev/video0", NULL, &pInputOptions)) < 0) {
 char errMsg[1024] = {0};
 std::cout << "Cannot open input file '" << filename << "', Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 return ret;
 }
#endif

 ifmt_ctx->flags |= AVFMT_FLAG_NONBLOCK;

 if ((ret = avformat_find_stream_info(ifmt_ctx, NULL)) < 0) {
 char errMsg[1024] = {0};
 std::cout << "Cannot find input stream information. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 return ret;
 }

 ret = av_find_best_stream(ifmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &decoder, 0);
 if (ret < 0) {
 char errMsg[1024] = {0};
 std::cout << "Cannot find a video stream in the input file. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 return ret;
 }
 video_stream = ret;

 if (!(decoder_ctx = avcodec_alloc_context3(decoder)))
 return AVERROR(ENOMEM);

 video = ifmt_ctx->streams[video_stream];
 if ((ret = avcodec_parameters_to_context(decoder_ctx, video->codecpar)) < 0) {
 char errMsg[1024] = {0};
 std::cout << "avcodec_parameters_to_context error. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 return ret;
 }

 decoder_ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);
 if (!decoder_ctx->hw_device_ctx) {
 std::cout << "A hardware device reference create failed." << std::endl;
 return AVERROR(ENOMEM);
 }
 decoder_ctx->get_format = get_vaapi_format;

 if ((ret = avcodec_open2(decoder_ctx, decoder, NULL)) < 0)
 {
 char errMsg[1024] = {0};
 std::cout << "Failed to open codec for decoding. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 }

 return ret;
}

static int encode_write(AVPacket *enc_pkt, AVFrame *frame)
{
 int ret = 0;

 av_packet_unref(enc_pkt);

 AVHWDeviceContext *pHwDevCtx = reinterpret_cast(encoder_ctx->hw_device_ctx);
 AVHWFramesContext *pHwFrameCtx = reinterpret_cast(encoder_ctx->hw_frames_ctx);

 if ((ret = avcodec_send_frame(encoder_ctx, frame)) < 0) {
 char errMsg[1024] = {0};
 std::cout << "Error during encoding. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 goto end;
 }
 while (1) {
 ret = avcodec_receive_packet(encoder_ctx, enc_pkt);
 if (ret)
 break;

 enc_pkt->stream_index = 0;
 av_packet_rescale_ts(enc_pkt, ifmt_ctx->streams[video_stream]->time_base,
 ofmt_ctx->streams[0]->time_base);
 ret = av_interleaved_write_frame(ofmt_ctx, enc_pkt);
 if (ret < 0) {
 char errMsg[1024] = {0};
 std::cout << "Error during writing data to output file. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 return -1;
 }
 }

end:
 if (ret == AVERROR_EOF)
 return 0;
 ret = ((ret == AVERROR(EAGAIN)) ? 0:-1);
 return ret;
}

static int dec_enc(AVPacket *pkt, const AVCodec *enc_codec, AVCodecContext *pDecCtx)
{
 AVFrame *frame;
 int ret = 0;

 ret = avcodec_send_packet(decoder_ctx, pkt);
 if (ret < 0) {
 char errMsg[1024] = {0};
 std::cout << "Error during decoding. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 return ret;
 }

 while (ret >= 0) {
 if (!(frame = av_frame_alloc()))
 return AVERROR(ENOMEM);

 ret = avcodec_receive_frame(decoder_ctx, frame);
 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
 av_frame_free(&frame);
 return 0;
 } else if (ret < 0) {
 char errMsg[1024] = {0};
 std::cout << "Error while decoding. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 goto fail;
 }

 if (!initialized) {
 AVHWFramesContext *pHwFrameCtx = reinterpret_cast(decoder_ctx->hw_frames_ctx);
 
 /* we need to ref hw_frames_ctx of decoder to initialize encoder's codec.
 Only after we get a decoded frame, can we obtain its hw_frames_ctx */
 encoder_ctx->hw_frames_ctx = av_buffer_ref(pDecCtx->hw_frames_ctx);
 if (!encoder_ctx->hw_frames_ctx) {
 ret = AVERROR(ENOMEM);
 goto fail;
 }
 /* set AVCodecContext Parameters for encoder, here we keep them stay
 * the same as decoder.
 * xxx: now the sample can't handle resolution change case.
 */
 if(encoder_ctx->time_base.den == 1 && encoder_ctx->time_base.num == 0)
 {
 encoder_ctx->time_base = av_inv_q(ifmt_ctx->streams[video_stream]->avg_frame_rate);
 }
 else
 {
 encoder_ctx->time_base = av_inv_q(decoder_ctx->framerate);
 }
 encoder_ctx->pix_fmt = AV_PIX_FMT_VAAPI;
 encoder_ctx->width = decoder_ctx->width;
 encoder_ctx->height = decoder_ctx->height;

 if ((ret = avcodec_open2(encoder_ctx, enc_codec, NULL)) < 0) {
 char errMsg[1024] = {0};
 std::cout << "Failed to open encode codec. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 goto fail;
 }

 if (!(ost = avformat_new_stream(ofmt_ctx, enc_codec))) {
 std::cout << "Failed to allocate stream for output format." << std::endl;
 ret = AVERROR(ENOMEM);
 goto fail;
 }

 ost->time_base = encoder_ctx->time_base;
 ret = avcodec_parameters_from_context(ost->codecpar, encoder_ctx);
 if (ret < 0) {
 char errMsg[1024] = {0};
 std::cout << "Failed to copy the stream parameters. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 goto fail;
 }

 /* write the stream header */
 if ((ret = avformat_write_header(ofmt_ctx, NULL)) < 0) {
 char errMsg[1024] = {0};
 std::cout << "Error while writing stream header. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 goto fail;
 }

 initialized = 1;
 }

 if ((ret = encode_write(pkt, frame)) < 0)
 std::cout << "Error during encoding and writing." << std::endl;

fail:
 av_frame_free(&frame);
 if (ret < 0)
 return ret;
 }
 return 0;
}

int main(int argc, char **argv)
{
 const AVCodec *enc_codec;
 int ret = 0;
 AVPacket *dec_pkt;

 if (argc != 4) {
 fprintf(stderr, "Usage: %s <input file="file" /> <encode codec="codec"> <output file="file">\n"
 "The output format is guessed according to the file extension.\n"
 "\n", argv[0]);
 return -1;
 }

 ret = av_hwdevice_ctx_create(&hw_device_ctx, AV_HWDEVICE_TYPE_VAAPI, NULL, NULL, 0);
 if (ret < 0) {
 char errMsg[1024] = {0};
 std::cout << "Failed to create a VAAPI device. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 return -1;
 }

 dec_pkt = av_packet_alloc();
 if (!dec_pkt) {
 std::cout << "Failed to allocate decode packet" << std::endl;
 goto end;
 }

 if ((ret = open_input_file(argv[1])) < 0)
 goto end;

 if (!(enc_codec = avcodec_find_encoder_by_name(argv[2]))) {
 std::cout << "Could not find encoder '" << argv[2] << "'" << std::endl;
 ret = -1;
 goto end;
 }

 if ((ret = (avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, argv[3]))) < 0) {
 char errMsg[1024] = {0};
 std::cout << "Failed to deduce output format from file extension. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 goto end;
 }

 if (!(encoder_ctx = avcodec_alloc_context3(enc_codec))) {
 ret = AVERROR(ENOMEM);
 goto end;
 }

 ret = avio_open(&ofmt_ctx->pb, argv[3], AVIO_FLAG_WRITE);
 if (ret < 0) {
 char errMsg[1024] = {0};
 std::cout << "Cannot open output file. Error code: " << av_make_error_string(errMsg, 1024, ret) << std::endl;
 goto end;
 }

 /* read all packets and only transcoding video */
 while (ret >= 0) {
 if ((ret = av_read_frame(ifmt_ctx, dec_pkt)) < 0)
 break;

 if (video_stream == dec_pkt->stream_index)
 ret = dec_enc(dec_pkt, enc_codec, decoder_ctx);

 av_packet_unref(dec_pkt);
 }

 /* flush decoder */
 av_packet_unref(dec_pkt);
 ret = dec_enc(dec_pkt, enc_codec, decoder_ctx);

 /* flush encoder */
 ret = encode_write(dec_pkt, NULL);

 /* write the trailer for output stream */
 av_write_trailer(ofmt_ctx);

end:
 avformat_close_input(&ifmt_ctx);
 avformat_close_input(&ofmt_ctx);
 avcodec_free_context(&decoder_ctx);
 avcodec_free_context(&encoder_ctx);
 av_buffer_unref(&hw_device_ctx);
 av_packet_free(&dec_pkt);
 return ret;
}
</output></encode></iostream>

And the content of the associated CMakeLists.txt file to build it using gcc :


cmake_minimum_required(VERSION 3.5)

include(FetchContent)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

set(CMAKE_VERBOSE_MAKEFILE ON)

SET (FFMPEG_HW_TRANSCODE_INCS
 ${CMAKE_CURRENT_LIST_DIR})

include_directories(
 ${CMAKE_INCLUDE_PATH}
 ${CMAKE_CURRENT_LIST_DIR}
)

project(FFmpeg_HW_transcode LANGUAGES CXX)

set(CMAKE_CXX_FLAGS "-Wall -Werror=return-type -pedantic -fPIC -gdwarf-4")
set(CMAKE_CPP_FLAGS "-Wall -Werror=return-type -pedantic -fPIC -gdwarf-4")

set(EXECUTABLE_OUTPUT_PATH "${CMAKE_CURRENT_LIST_DIR}/build/${CMAKE_BUILD_TYPE}/FFmpeg_HW_transcode")
set(LIBRARY_OUTPUT_PATH "${CMAKE_CURRENT_LIST_DIR}/build/${CMAKE_BUILD_TYPE}/FFmpeg_HW_transcode")

add_executable(${PROJECT_NAME})

target_sources(${PROJECT_NAME} PRIVATE
 vaapi_transcode.cpp)

target_link_libraries(${PROJECT_NAME}
 -L${CMAKE_CURRENT_LIST_DIR}/../build/${CMAKE_BUILD_TYPE}/FFmpeg_HW_transcode
 -lavdevice
 -lavformat
 -lavutil
 -lavcodec)


Has anyone tried to do this kind of stuff ?


Thanks for your help.


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