Ich habe diese Woche eine Mail von Apple bekommen, in der sie offiziell neue Podcast-Richtlinien bzw. Empfehlungen aussprechen.
Habt ihr diese Mail auch bekommen? Was haltet ihr davon, sollte man sich entsprechend umstellen bzw. sich daran halten?
Man sollte nicht vergessen, dass Apple mit dem iTunes Podcast Verzeichnis und der iOS Podcast App immer noch den mit Abstand größten Marktanteil hat, da kann sonst kein Podcast-Verzeichnis oder -App mithalten, die meisten Podcasts werden gefunden über das iTunes Podcast Verzeichnis bzw. mit der iOS Podcasts App gehört.
Und sie nennen es zwar noch Empfehlung, aber wer weiß, was passiert, wenn man sich langfristig nicht daran hält - vielleicht wird dann der Podcast (einzelne Episoden oder gar der ganze Podcast) gesperrt oder einfach in der Suche kaum noch angezeigt.
Solltet ihr diese Mail nicht bekommen haben oder euch nicht durch die mehreren Seiten klicken wollen, kopiere ich den Text hier nochmal unten mit allen Punkten rein.
Es geht zum Beispiel darum, dass Apple „strongly recommended“, dass man künftig lieber AAC statt MP3 als Audio-Format nutzen solle und wenn dem so sei, dann am besten als MP4-Datei. Ebenso scheinen sie künftig bestimmte Lautstärke-Bereiche zu bevorzugen oder gar dass man diese als ID3-Tags speichert, damit Podcatcher immer automatisch gleich die richtige Einstellung haben.
Vielleicht habe ich auch manche Sachen nicht ganz richtig verstanden, weil vieles mit den Lautstärke-Fachbegriffen für mich eher böhmische Dörfer darstellt, aber darum würde ich gerne auch euren Input dazu hören.
Mail von Apple:
Betreff: New Marketing and Authoring Best Practices
Dear Podcast Provider,
To improve your experience with Apple Podcasts, we want to share the following announcements and information.
Marketing Best Practices Website
Find out what it takes to grow your audience. The new Apple Podcasts Marketing Best Practices website offers tips and tools used by big-name shows and indies alike. Learn all about fundamentals, audience development, Apple tools and resources, as well as common mistakes to avoid.
Podcasts Authoring Best Practices
To help your podcast sound its best on HomePod and on Apple Podcasts, we encourage you to read our new Podcasts Authoring Best Practices. Use these guidelines on formats, levels, and loudness metadata to create the best possible quality and file size tradeoffs while ensuring a pleasant and distortion-free experience for listeners.
If you have any questions, just contact us.
Regards,
The Apple Podcasts team
Link zur Apple Podcast Marketing Best Practices-Website: https://podcaster.apple.com/
Hier die Texte von den Podcast Authoring Best Practices: https://help.apple.com/itc/podcastsbestpractices/#/itcd01498138
Apple wants to create a better experience in Apple Podcasts, not only for you, podcast providers, but also for your listeners and subscribers. In addition to general podcast authoring guidelines, this best practice guide elaborates on:
You can use these guidelines to create the best possible quality and file size tradeoffs while ensuring a pleasant and distortion-free listening experience.
For efficient use of networking bandwidth when distributing podcasts, the audio content is typically encoded or compressed in a lossy format like AAC or MP3 yielding significant file size reductions. The ratios of the uncompressed to the compressed file sizes are in the order of 10 to 16.
Although MP3 is the most commonly used format for audio podcasts, we strongly recommend using AAC over MP3. Today, there are no technical limitations which would preclude an AAC podcast to be played back on any device. When choosing AAC, we recommend the use of MP4 formats over the ADTS format. ADTS can have streaming usage but doesn’t allow for accurate seeking, whereas the MP4 file format does.
This compression process might introduce audible artifacts if the sample rate (expressed in kilohertz, kHz), the number of channels, and bit rate (expressed in kilobits per second, kbps) tradeoffs aren’t correctly selected. Smaller bit rates will result in smaller files which will be transmitted faster and more efficiently but can generate audible artifacts that won’t be recoverable at the decoding or playback stage. Larger bits, will result in larger files and in an increased audio quality, will require more bandwidth for transmission. The best compromise is to select the appropriate bit rate given the sample rate and the number of channels of the content to be encoded. Alternatively, if the bit rate is constrained, the signal might have to be pre-conditioned. To do so, either reduce the sample rate, for example, 48 to 24 kHz or, reduce the number of channels from stereo to mono, or both.
The table below summarizes the recommended bit rate ranges from the most commonly used sample rates and channel configurations. These bit rates apply to both the AAC and MP3 formats. For the same bit rate, AAC will result in better audio quality.
| Number of channels | 22.05 / 24 kHz | 44.1 / 48 kHz |
|---|---|---|
| 1 (mono) | 40 - 80 kbps | 64 - 128 kbps |
| 2 (stereo) | 80 - 160 kbps | 128 - 256 kbps |
For consistency and pleasant listening experience, keep your general loudness and peak amplitudes within specific limits. Content that is heavily compressed and amplified might be too loud, will lack the dynamic range, and can introduce harmonic distortions. Alternatively, content with low audio levels will have dynamic range but will be too quiet, inaudible, or unintelligible in the case of spoken content. In either case, a listener might have to adjust the playback volume to a comfortable level.
To prevent such content-driven volume adjustments, we strongly recommend that the audio signals are pre-conditioned in such a way that the overall loudness remains around -16 dB LKFS, with a +/- 1 dB tolerance and that the true-peak value doesn’t exceed -1 dB FS. The LKFS and true-peak values are calculated according to the ITU-R BS.1770-4 recommendation. The pre-conditioning steps need to occur before the encoding process. We recommend this because audio compression algorithms typically don’t modify the loudness and might clip the signal if the recommended true-peak value is not respected.
In some cases, you can embed specific podcast data such as the underlying loudness, dynamic range, and peak level information of your podcast. To do so, modify the ID3 tags of an MP3 file or in the header of an MP4 file.
The benefit of having this data available within your file is that it allows playback engines to automatically and precisely adjust levels to a predetermined playback or target level. Apple uses this mechanism via the Sound Check setting in the iOS Music app.
When enabled, content containing loudness or Sound Check metadata will consistently have playback levels at -16 dB. It is important to note that MP3 files created with the iTunes Export function will have Sound Check metadata.
