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• How to use audio frame after decode mp3 file using pyav, ffmpeg, python

  2 janvier 2021, par Long Tran Dai

  I am using using python with pyav, ffmpeg to decode mp3 in the memory. I know there are some other way to do it, like pipe ffmpeg command. However, I would like to explore pyav and ffmpeg API. So I have the following code. It works but the sound is very noisy, although hearable :

  


  import numpy as np&#xA;import av # to convert mp3 to wav using ffmpeg&#xA;import pyaudio # to play music&#xA;&#xA;mp3_path = &#x27;D:/MyProg/python/SauTimThiepHong.mp3&#x27;&#xA;&#xA;def decodeStream(mp3_path):&#xA;  # Run NOT OK&#xA;  &#xA;  container = av.open(mp3_path)&#xA;  stream = next(s for s in container.streams if s.type == &#x27;audio&#x27;)&#xA;  frame_count = 0&#xA;  data = bytearray()&#xA;  for packet in container.demux(stream):&#xA;    # <class>&#xA;    # We need to skip the "flushing" packets that `demux` generates.&#xA;    #if frame_count == 5000 : break         &#xA;    if packet.dts is None:&#xA;        continue&#xA;    for frame in packet.decode():   &#xA;        #&#xA;        # type(frame) : <class>&#xA;        #frame.samples = 1152 : 1152 diem du lieu : Number of audio samples (per channel)&#xA;        # moi frame co size = 1152 (diem) * 2 (channels) * 4 (bytes / diem) = 9216 bytes&#xA;        # 11021 frames&#xA;        #arr = frame.to_ndarray() # arr.nbytes = 9216&#xA;&#xA;        #channels = []  &#xA;        channels = frame.to_ndarray().astype("float16")&#xA;        #for plane in frame.planes:&#xA;            #channels.append(plane.to_bytes()) #plane has 4 bytes / sample, but audio has only 2 bytes&#xA;        #    channels.append(np.frombuffer(plane, dtype=np.single).astype("float16"))&#xA;            #channels.append(np.frombuffer(plane, dtype=np.single)) # kieu np.single co 4 bytes&#xA;        if not frame.is_corrupt:&#xA;            #data.extend(np.frombuffer(frame.planes[0], dtype=np.single).astype("float16")) # 1 channel: noisy&#xA;            # type(planes) : <class>&#xA;            frame_count &#x2B;= 1&#xA;            #print( &#x27;>>>> %04d&#x27; % frame_count, frame)   &#xA;            #if frame_count == 5000 : break     &#xA;            # mix channels:&#xA;            for i in range(frame.samples):                &#xA;                for ch in channels: # dec_ctx->channels&#xA;                    data.extend(ch[i]) #noisy&#xA;                    #fwrite(frame->data[ch] &#x2B; data_size*i, 1, data_size, outfile)&#xA;  return bytes(data)&#xA;</class></class></class>

  


  I use pipe ffmpeg to get decoded data to compare and find they are different :

  


  def RunFFMPEG(mp3_path, target_fs = "44100"):
    # Run OK
    import subprocess
    # init command
    ffmpeg_command = ["ffmpeg", "-i", mp3_path,
                   "-ab", "128k", "-acodec", "pcm_s16le", "-ac", "0", "-ar", target_fs, "-map",
                   "0:a", "-map_metadata", "-1", "-sn", "-vn", "-y",
                   "-f", "wav", "pipe:1"]
    # excute ffmpeg command
    pipe = subprocess.run(ffmpeg_command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, bufsize= 10**8)
    # debug
    #print(pipe.stdout, pipe.stderr)
    # read signal as numpy array and assign sampling rate
    #audio_np = np.frombuffer(buffer=pipe.stdout, dtype=np.uint16, offset=44)
    #audio_np = np.frombuffer(buffer=pipe.stdout, dtype=np.uint16)
    #sig, fs  = audio_np, target_fs
    #return audio_np
    return pipe.stdout[78:]     


  


  Then I use pyaudio to play data and find it very noisy

  


  p = pyaudio.PyAudio()
streamOut = p.open(format=pyaudio.paInt16, channels=2, rate= 44100, output=True)
#streamOut = p.open(format=pyaudio.paInt16, channels=1, rate= 44100, output=True)

mydata = decodeStream(mp3_path)
print("bytes of mydata = ", len(mydata))
#print("bytes of mydata = ", mydata.nbytes)

ffMpegdata = RunFFMPEG(mp3_path)
print("bytes of ffMpegdata = ", len(ffMpegdata)) 
#print("bytes of ffMpegdata = ", ffMpegdata.nbytes)

minlen = min(len(mydata), len(ffMpegdata))
print("mydata == ffMpegdata", mydata[:minlen] == ffMpegdata[:minlen]) # ffMpegdata.tobytes()[:minlen] )

#bytes of mydata =  50784768
#bytes of ffMpegdata =  50784768
#mydata == ffMpegdata False

streamOut.write(mydata)
streamOut.write(ffMpegdata)
streamOut.stop_stream()
streamOut.close()
p.terminate()


  


  Please help me to understand decoded frame of pyav api (after for frame in packet.decode() :). Should it be processed more ? or I have some error ?

  


  It makes me crazy for 3 days. I could not guess where to go.

  


  Thank you very much.

  


• How to contribute to open source, for companies

  18 octobre 2010, par Dark Shikari — development, open source, x264

  I have seen many nigh-incomprehensible attempts by companies to contribute to open source projects, including x264. Developers are often simply boggled, wondering why the companies seem incapable of proper communication. The companies assume the developers are being unreceptive, while the developers assume the companies are being incompetent, idiotic, or malicious. Most of this seems to boil down to a basic lack of understanding of how open source works, resulting in a wide variety of misunderstandings. Accordingly, this post will cover the dos and don’ts of corporate contribution to open source.

  Do : contact the project using their preferred medium of communication.

  Most open source projects use public methods of communication, such as mailing lists and IRC. It’s not the end of the world if you mistakenly make contact with the wrong people or via the wrong medium, but be prepared to switch to the correct one once informed ! You may not be experienced using whatever form of communication the project uses, but if you refuse to communicate through proper channels, they will likely not be as inclined to assist you. Larger open source projects are often much like companies in that they have different parts to their organization with different roles. Don’t assume that everyone is a major developer !

  If you don’t know what to do, a good bet is often to just ask someone.

  Don’t : contact only one person.

  Open source projects are a communal effort. Major contributions are looked over by multiple developers and are often discussed by the community as a whole. Yet many companies tend to contact only a single person in lieu of dealing with the project proper. This has many flaws : to begin with, it forces a single developer (who isn’t paid by you) to act as your liaison, adding yet another layer between what you want and the people you want to talk to. Contribution to open source projects should not be a game of telephone.

  Of course, there are exceptions to this : sometimes a single developer is in charge of the entirety of some particular aspect of a project that you intend to contribute to, in which case this might not be so bad.

  Do : make clear exactly what it is you are contributing.

  Are you contributing code ? Development resources ? Money ? API documentation ? Make it as clear as possible, from the start ! How developers react, which developers get involved, and their expectations will depend heavily on what they think you are providing. Make sure their expectations match reality. Great confusion can result when they do not.

  This also applies in the reverse — if there’s something you need from the project, such as support or assistance with development of your patch, make that explicitly clear.

  Don’t : code dump.

  Code does not have intrinsic value : it is only useful as part of a working, living project. Most projects react very negatively to large “dumps” of code without associated human resources. That is, they expect you to work with them to finalize the code until it is ready to be committed. Of course, it’s better to work with the project from the start : this avoids the situation of writing 50,000 lines of code independently and then finding that half of it needs to be rewritten. Or, worse, writing an enormous amount of code only to find it completely unnecessary.

  Of course, the reverse option — keeping such code to yourself — is often even more costly, as it forces you to maintain the code instead of the official developers.

  Do : ignore trolls.

  As mentioned above, many projects use public communication methods — which, of course, allow anyone to communicate, by nature of being public. Not everyone on a project’s IRC or mailing list is necessarily qualified to officially represent the project. It is not too uncommon for a prospective corporate contributor to be turned off by the uninviting words of someone who isn’t even involved in the project due to assuming that they were. Make sure you’re dealing with the right people before making conclusions.

  Don’t : disappear.

  If you are going to try to be involved in a project, you need to stay in contact. We’ve had all too many companies who simply disappear after the initial introduction. Some tell us that we’ll need an NDA, then never provide it or send status updates. You may know why you’re not in contact — political issues at the company, product launch crunches, a nice vacation to the Bahamas — but we don’t ! If you disappear, we will assume that you gave up.

  Above all, don’t assume that being at a large successful company makes you immune to these problems. If anything, these problems seem to be the most common at the largest companies. I didn’t name any names in this post, but practically every single one of these rules has been violated at some point by companies looking to contribute to x264. In the larger scale of open source, these problems happen constantly. Don’t fall into the same traps that many other companies have.

  If you’re an open source developer reading this post, remember it next time you see a company acting seemingly nonsensically in an attempt to contribute : it’s quite possible they just don’t know what to do. And just because they’re doing it wrong doesn’t mean that it isn’t your responsibility to try to help them do it right.

• How to track Google AdWords campaigns with Piwik

  19 décembre 2017, par InnoCraft

  In 2016, Google AdWords was the most popular ad service on earth. As a result, it may be your first source for ad spending. Are you interested in knowing whether you are making a profit out of it ? Would you like to know how to track users coming from AdWords with Piwik efficiently ? This is what this article is about.

  

  What you need to know about Google AdWords

  By default, each ad you create in Google AdWords is not tracked. Even worse than that, every click on your ad is identified in Piwik as an organic result coming from Google with the following value : “Keyword not defined”.

  To make it simple, if you do not track your AdWords campaigns both your paid and organic traffic will be biased within your Piwik account. It will be impossible for you to measure your return on investment and it means that you are throwing your money down the drain.

  In order to avoid this, we will show you how to track Google AdWords traffic into Piwik.

  How to track paid Google AdWords campaigns into Piwik

  If you want to analyze Google AdWords campaigns within Piwik properly, you need to add additional tracking parameters to the final URL of each of your ads.

  We recommend using the following tool to add the needed additional tracking parameters : https://piwik.org/docs/tracking-campaigns-url-builder/

  You will then be able to push additional data to Piwik such as :

  • pk_campaign : the name of your ad campaign
  • pk_kwd : the keyword associated to this campaign
  • pk_source : the source of your campaign
  • pk_medium : the type of source, in our case either cpc, cpm, cpa
  • pk_content : the content of your ad

  If your campaign URL looks like this : https://your-website.com/, your campaign URL will then look like this after adding the campaign parameters :

  https://your-website.com/?pk_campaign=Name-Of-Your-Campaign&pk_kwd=Your-Keyword&pk_source=google&pk_medium=cpc&pk_content=My-Ad-Headline

  As each ad URL can be fired by different keywords and can correspond to different campaigns or headlines, you will need to customize the campaign parameters for each URL.

  Customizing all of your URLs individually would take you a lot of time under circumstances. That’s why you should know, that each URL parameter can be filled automatically in AdWords with a feature called “Tracking template”.

  Simplifying the campaign URL parameters with tracking templates

  You can define tracking templates either at the account, campaign or ad group level. For example, by using a tracking template at the account level, all your campaigns will have the same landing page with the URL parameters you defined in the tracking template. By defining it at the campaign level, it means that all your ad groups within the campaign will have the same landing page and so on and so forth. Any tracking template defined in a campaign, will overwrite a tracking template defined at the account level.

  Tracking template at the account level

  To edit the template at the account level, you need to click on “Settings”, then click on the “Account” settings tab and define your tracking template pattern. For example :

  https://your-website.com/?url={lpurl}&pk_campaign=AdWords&pk_kwd=Your-Keyword&pk_source=google&pk_medium=cpc&pk_content=My-Ad-Headline

  

  This will apply to all your URLs within your account. So it is only useful if your website domain is the same across all your ads. The URL parameter is compulsory here.

  It can be limiting to have a static value for “pk_campaign” and “pk_kwd” so Google allows you to use dynamic insertion, such as follows :

  https://your-landing-page.com/?url={lpurl}&pk_campaign={campaignid}&pk_kwd={keyword}&pk_source=google&pk_medium=cpc&pk_content={creative}

  The “keyword” means that the data is automatically replaced with the keyword which fired the ad within your account.

  Visit the following page if you want to know more about the different dynamic tags that AdWords supports : https://support.google.com/adwords/answer/6305348#urlinsertion

  Tracking template at the campaign level

  If you wish to define a tracking template at the campaign level, you will find this option within the “Campaign” settings under the campaign URL options :

  

  Tracking template at the Ad Group level

  You can also set it at the Ad Group level within the “Ad Group” settings :

  

  As Google mentions : “If you set up URL options at the campaign level, ad group level, or ad level, those settings will override the account-level options“.

  Now that your URLs are properly configured, you will be able to analyze AdWords traffic performances within Piwik once a click is coming from those sources.

  

  Did you like this article ? If yes, do not hesitate to share it or give us your feedback about the topic you would like us to write about.