AVBlocks™ Blog

AVBlocks v3.4 - What’s New

2026-09-30T00:00:00-07:00

AVBlocks 3.4 runs natively on arm64, adds HEVC / H.265 AU stream support, and introduces two new ways to use AVBlocks: AVBlocks Plus, a fluent C++ API, and AVBlocks for Python.

Platforms

arm64 support for AVBlocks C++ and AVBlocks .NET on Windows, macOS (Apple Silicon) and Ubuntu Linux
The C++ and .NET samples build for both x64 and arm64 (bin/<arch>/net10.0 for .NET)
download-sdk-and-assets scripts in the sample repositories pick the SDK that matches the host architecture

API

AVBlocks Plus: a modern C++ fluent API on top of the AVBlocks core library. See the wiki and the API docs
AVBlocks for Python: Python bindings (the avblocks package) for Python 3.12 or higher, on x64 and arm64 for Windows, macOS and Linux. See the wiki and the API docs
HEVC / H.265: decode and encode AU streams
MP4: demux H.265 streams from an MP4 container

Samples

C++ and .NET:

HEVC / H.265: enc_hevc_file, dec_hevc_file, dec_hevc_au and dump_hevc_au (and enc_hevc_pull for C++)
VP8: enc_vp8_file and dec_vp8_file
VP9: enc_vp9_file and dec_vp9_file
Vorbis: enc_vorbis_file and dec_vorbis_file
Opus: enc_opus_file and dec_opus_file (and enc_opus_pull for C++)
WebM: demux_webm_file and mux_webm_file

C++ only:

mux_mp4_fs_file: mux an MP4 file with the FastStart option

.NET only:

enc_avc_push: encode a YUV file to H.264 with Transcoder.Push
simple_converter: transcode H.264 video to H.265
simple_audio_upsample, simple_video_crop, simple_video_pad, simple_video_upscale and simple_video_framerate: common audio and video conversions

Python:

Samples for audio and video encoding and decoding, muxing and demuxing, media information and video processing

Docs

New wikis for AVBlocks Plus and AVBlocks for Python
New API docs for AVBlocks Plus and AVBlocks for Python
The .NET wiki is updated for arm64, with new installation and setup instructions for Windows, macOS and Linux

Fixes

TIFF images could not be read on Ubuntu 26.04
VP8 / VP9: the picture type is now set from the key frame status

Get it

AVBlocks Core and AVBlocks .NET Core 3.4 demo releases
Samples: C++, .NET, Fluent C++ and Python

See the release notes for the complete list of changes.

AVBlocks v3.3 - What’s New

2026-01-21T00:00:00-08:00

AVBlocks 3.3 adds VP9 video and Opus audio, brings both into the WebM container, and adds support for .NET 10.

Codecs and containers

VP9: video encoding and decoding
Opus: audio encoding and decoding
WebM: mux and demux VP9 video
WebM: mux and demux Opus audio
Ogg: mux Opus audio
IVF: read and write VP8 / VP9 video in the Duck IVF container

API

.NET: support for .NET 10 (LTS) on Windows, macOS and Linux
Improved stream reading efficiency: input streams are now read 2048 bytes at a time

Samples

.NET: the .NET samples now include all samples from the C++ SDK
.NET: the samples target .NET 10
C++: updated instructions for Ubuntu 22.04 and 24.04
C++: instructions for building the samples directly with cmake on Windows, macOS and Linux

Docs

The wikis have new topics for VP9 video, Opus audio and the WebM container. The same topics for .NET: VP9, Opus, WebM

Fixes

Vorbis: MediaInfo reported bitsPerSample = 0 for Vorbis streams in a WebM container

Get it

AVBlocks Core and AVBlocks .NET Core 3.3 demo releases
Samples: C++ and .NET

See the release notes for the complete list of changes.

How to configure output socket for MP3 encoding in .NET

2024-05-11T00:00:00-07:00

Here is a quick snippet for configuring the output socket of a Transcoder for MP3 encoding using C#.

Diagram

Code

This is the code for the output socket:

static MediaSocket CreateOutputSocket(Options opt)
{
    AudioStreamInfo asi = new AudioStreamInfo();
    asi.StreamType = StreamType.MpegAudio;
    asi.StreamSubType = StreamSubType.MpegAudioLayer3;

    // The default bitrate is 128000. You can set it to 192000, 256000, etc.
    // asi.Bitrate = 192000;

    // You can change the sampling rate and the number of the channels
    // asi.SampleRate = 44100;
    // asi.Channels = 1;

    MediaPin pin = new MediaPin();
    pin.StreamInfo = asi;

    MediaSocket socket = new MediaSocket();
    socket.StreamType = StreamType.MpegAudio;
    socket.StreamSubType = StreamSubType.MpegAudioLayer3;

    socket.Pins.Add(pin);

    // output to a file
    socket.File = opt.OutputFile;

    return socket;
}

The complete program is available on GitHub:

enc_mp3_file

How to configure output socket for AAC / ADTS encoding in C++

2024-05-08T00:00:00-07:00

Here is a quick snippet for configuring the output socket of a Transcoder for Advanced Audio Coding (AAC) / Audio Data Transport Stream (ADTS) encoding using C++.

Diagram

Code

This is the code for the output socket:

primo::ref<MediaSocket> createOutputSocket(Options& opt)
{
    // create stream info to describe the output audio stream
    auto asi = primo::make_ref(Library::createAudioStreamInfo());
    asi->setStreamType(StreamType::AAC);
    asi->setStreamSubType(StreamSubType::AAC_ADTS);

    // You can change the sampling rate and the number of the channels
    // asi->setSampleRate(44100);
    // asi->setChannels(1);

    // create a pin using the stream info 
    auto pin = primo::make_ref(Library::createMediaPin());
    pin->setStreamInfo(asi.get());

    // finally create a socket for the output container format 
    // which in this case is AAC packaged as Audio Data Transport Stream (ADTS)
    auto socket = primo::make_ref(Library::createMediaSocket());
    socket->setStreamType(StreamType::AAC);
    socket->setStreamSubType(StreamSubType::AAC_ADTS);

    socket->pins()->add(pin.get());

    // output to a file
    auto output_file = primo::ustring(opt.outputFile);
    socket->setFile(output_file);
    
    return socket;
}

The complete program is available on GitHub:

How to configure output socket for MP3 encoding in C++

2024-05-06T00:00:00-07:00

Here is a quick snippet for configuring the output socket of a Transcoder for MP3 encoding using C++.

Diagram

Code

This is the code for the output socket:

primo::ref<MediaSocket> createOutputSocket(Options& opt)
{
    // create stream info to describe the output audio stream
    auto asi = primo::make_ref(Library::createAudioStreamInfo());
    asi->setStreamType(StreamType::MPEG_Audio);
    asi->setStreamSubType(StreamSubType::MPEG_Audio_Layer3);

    // The default bitrate is 128000. You can set it to 192000, 256000, etc.
    // asi->setBitrate(192000);

    // Optionally set the sampling rate and the number of the channels, e.g. 44.1 Khz, Mono 
    // asi->setSampleRate(44100);
    // asi->setChannels(1);

    // create a pin using the stream info 
    auto pin = primo::make_ref(Library::createMediaPin());
    pin->setStreamInfo(asi.get());

    // the pin allows you to specify additional parameters for the encoder 
    // for example, change the stereo mode, e.g. Joint Stereo
    // pin->params()->addInt(Param::Encoder::Audio::MPEG1::StereoMode, StereoMode::Joint);

    // finally create a socket for the output container format which is MP3 in this case
    auto socket = primo::make_ref(Library::createMediaSocket());
    socket->setStreamType(StreamType::MPEG_Audio);
    socket->setStreamSubType(StreamSubType::MPEG_Audio_Layer3);

    socket->pins()->add(pin.get());

    // output to a file
    auto output_file = primo::ustring(opt.outputFile);
    socket->setFile(output_file);

    return socket;
}

The complete program is available on GitHub:

AVBlocks v3 - What’s New

2023-07-05T00:00:00-07:00

API

Remove 32-bit application support (C++ and .NET)
C++: Refactor API headers to use lowercase file names and subdirectories for namespaces
.NET: New AVBlocks .NET SDK for macOS and Linux (based on .NET Core 6+)
Distribute the AVBlocks Core and AVBlocks .NET Core through GitHub

Samples

Use cmake and Visual Studio Code for AVBlocks samples
GitHub repositories for AVBlocks samples
C++: Add enc_preset_file sample
.NET: Add enc_preset_file sample

Docs

Split the wiki to separate C++ and .NET sites

AVBlocks v2 - What’s New

2016-04-16T00:00:00-07:00

API

The MediaInfo object now implements the Block abstract interface.

Samples

New overlay_mp4_png_file sample. This sample shows how to place a watermark on a video file by blending a video file with a PNG image.

Controling H.264 decoding latency

2013-12-17T00:00:00-08:00

There is a new parameter in AVBlocks 1.8 called MaxDecFrameBuffering (corresponding to max_dec_frame_buffering from the AVC / H.264 standard). It controls the decoded picture buffer size of the decoder and indirectly affects the decoding latency.

Here are some key notes about using this parameter:

It must be set to the output pin (see the sample code below)
The supported values are 0 and 1. A negative value is ignored.
MaxDecFrameBuffering(0) achieves decoding latency of 0 frames for progressive streams and 1 frame for interlaced streams.
MaxDecFrameBuffering(1) achieves decoding latency of 1 frame both for progressive and interlaced streams.
If the stream has B-frames (or more precisely the total number of reference frames is greater than 1) the decoding will still succeed, but decoding latency will be greater than the required one, as a safety guard.
With MaxDecFrameBuffering (0|1) only one decoding thread is used, so it hurts performance and it must be used only when low decoding latency is the primary goal.

The following code can be used to set the MaxDecFrameBuffering parameter to an output pin:

void setH264DecodingLatency(primo::avblocks::MediaPin* pin, int32_t desiredLatency)
{
    using namespace primo::avblocks;
    using namespace primo::avblocks::Param;
    
    ParameterList* params ( Library::createParameterList() );
        IntParameter* maxDecFrameBuffering (Library::createIntParameter() );
            maxDecFrameBuffering->setName(Decoder::Video::H264::VUI::MaxDecFrameBuffering);
            maxDecFrameBuffering->setValue(desiredLatency);
            params->add(maxDecFrameBuffering);
        maxDecFrameBuffering->release();
        pin->setParams(params);
    params->release();
}

AVBlocks will not load if Wmvcore.dll is not present on user’s system

2013-09-09T00:00:00-07:00

Update: This issue has been fixed as of version 1.6.

Wmvcore.dll is standard on all editions of Windows Vista and Windows 7 with the exception of the “N” editions. The “N” editions are distributed in Europe and do not include Windows Media Player and its related technologies.

The following versions of Windows Vista or Window 7 are affected:

Windows 7 Starter N
Windows 7 Home Premium N
Windows 7 Professional N
Windows 7 Ultimate N
Windows Vista Home Basic N
Windows Vista Business N
Windows Vista Home Basic KN
Windows Vista Business KN

AVBlocks depends on the following Wmvcore.dll functions for ASF muxing and demuxing:

WMCreateProfileManager
WMCreateSyncReader
WMCreateWriter

We are fixing this issue by changing the code to load Wmvcore.dll on-demand. This fix will be available in AVBlocks 1.6.

How to set license string in AVBlocks

2013-05-29T00:00:00-07:00

This post assumes that you are using AVBlocks for .NET and you have purchased a license from the License Management site.

When you license a Primo Software product you usually get a license file in the email. The license file is basically a signed XML string that describes the products and features you have licensed. Then you have to provide the license to AVBlocks with the Library.SetLicense method.

Here is a code snippet in C#:

const string license = 
    @"<primoSoftware>
      <license version='1.0'>
        <token>abcdefghijklmnop</token>
        <revision>1</revision>
        <issueDate>2013-05-23</issueDate>
        <expireDate>2014-05-24</expireDate>
        <updateTime>2013-05-23 21:02:44</updateTime>
        <item id='avb-win'>
          <product>avb</product>
          <feature id='h264-enc' />
          <feature id='pcm' />
        </item>    
    	<signature>abcd-long-signature-string-here</signature>
      </license>
    </primoSoftware>";
    
Library.SetLicense(license);

The license above is for AVBlocks for Windows (avb-win) and includes the AVC / H.264 Encoder (h264-enc) and PCM Audio (pcm) features.

Then the following calls should return true for the license above:

Library.IsLicensed(null, null);
Library.IsLicensed(null, "h264-enc");
Library.IsLicensed(null, "pcm");
Library.IsLicensed("avb", "h264-enc");
Library.IsLicensed("avb", "pcm");

NOTES:

Calling Library.SetLicense on any of the AVBlocks Demo libraries will fail. The Demo version cannot be licensed. If you downloaded AVBlocks from www.avblocks.com then you have the Demo product. You need to get your AVBlocks copy from the Downloads section of the License Manager site.
You should be careful when formatting the license XML as it may become invalid.

Here are the rules:

It’s OK to reformat the blank space between the xml elements in the license (spaces, new lines) the way you wish.
It’s also OK to substitute the double quotes with single quotes (as shown in the example above), otherwise you need to escape the double quotes.
It’s NOT OK to reorder elements or change the letter case.

AVBlocks in demo mode

2012-10-20T00:00:00-07:00

The following restrictions apply when AVBlocks works in demo mode:

For video streams, a semi-transparent logo is overlaid on top of each video frame.
For audio streams, a short audio sample is mixed in the original track at random places.

The demo restrictions are removed when a valid XML license is passed to Library::setLicense API method.