> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cognigy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# PDF

When you use a PDF file as a Knowledge Source, you can split the PDF file into Knowledge Chunks with the following chunk strategies after uploading the file:

* [Default Chunk Strategy](#default-chunk-strategy)
* [Alternative Chunk Strategy](#alternative-chunk-strategy)

## Default Chunk Strategy

The Default Chunk Strategy extracts content from PDF and splits it into [Knowledge Chunks](/ai/agents/develop/knowledge-ai/knowledge-chunk/knowledge-chunk) based on a fixed token length and recognizes tables. Based on our research, the Default Chunk Strategy returns better structured results and works best with the **Top K** value set to 5 in the [Search Extract Output](/ai/agents/develop/node-reference/other-nodes/search-extract-output) Node.

## Alternative Chunk Strategy

The Alternative Chunk Strategy is effective when your original PDF is divided into paragraphs in a logical order separated by double line breaks. This strategy attempts to distinguish the structure, such as sections, and then splits each of them into one or more Knowledge Chunks.

To apply the Alternative Chunk Strategy, append `.preset_uiolc_ls.pdf` to the file name when you upload a file. For example, if you have a PDF file named `cognigy.pdf`, rename it to `cognigy.preset_uiolc_ls.pdf` before the upload. The `.preset_uiolc_ls` appendix triggers the Alternative Chunk Strategy after you upload the PDF file.

While processing the PDF file, Knowledge AI may omit complex elements such as visually intricate headers or lists and not include these elements in the Knowledge Chunks.

## Examples

Assume you have the following text from the [Cognigy blog](https://www.cognigy.com/blog) in a PDF file:

<Accordion title="PDF sample" defaultOpen="true">
  ```markdown theme={null}
  # Call Tracing: Unlock New Dimensions in VUX Optimization

  In the burgeoning field of voice technology, optimizing Voice User Experience (VUX) is a sophisticated endeavor fraught with unique challenges. 
  VUX designers confront intricate variables from timing nuances and intonation accuracy to the unpredictability of human speech and environmental interference.
  These factors often present hurdles that can transform an otherwise fluid dialogue into a disjointed exchange. 
  For enterprises aiming to scale and perfect their voice-enabled services, these are not mere technicalities but critical pivots on the customer experience journey.
  Recognizing this complex landscape, at Cognigy, we're excited to introduce the ultimate tool for developers and VUX designers in their quest for voice excellence: Call Tracing.

  ## Visualizing the Unseen: How Call Tracing Changes the Game 

  Traditionally, understanding and monitoring voice interaction requires painstaking analysis of transcriptions, user feedback, and basic audio playback. 
  Now, Cognigy's Call Tracing feature offers an actionable visualization of all activities taking place during the call, such as speech recognition and connections, together with the call recording waveforms. 
  This powerful tool grants VUX designers an unparalleled view of the dynamics of voice interactions.
  Event and soundwave visualization provides an analytical perspective that goes beyond the audio, giving professionals the ability to dissect and understand voice experiences at a granular level. 
  It brings critical elements to the forefront that might not be immediately evident in transcriptions or basic audio playback.
  ```
</Accordion>

You can download the [PDF sample](https://docscognigyassets.blob.core.windows.net/assets/call-tracing-sample.pdf).

### Example 1: Default Chunk Strategy

If you use the Default Chunk Strategy, Knowledge AI splits the PDF file into 3 equal Knowledge Chunks.

<Accordion title="Default Chunk Splitting" defaultOpen="true">
  1.

  ```markdown theme={null}
  Call Tracing: Unlock New
  Dimensions in VUX
  Optimization
  In the burgeoning field of voice technology, optimizing Voice User Experience (VUX) is a
  sophisticated endeavor fraught with unique challenges. VUX designers confront intricate
  variables from timing nuances and intonation accuracy to the unpredictability of human
  speech and environmental interference.
  These factors often present hurdles that can transform an otherwise fluid dialogue into a
  disjointed exchange. For enterprises aiming to scale and perfect their voice-enabled
  services, these are not mere technicalities but critical pivots on the customer experience
  journey.
  Recognizing this complex landscape, at
  ```

  2.

  ```markdown theme={null}
    Cognigy, we're excited to introduce the ultimate
  tool for developers and VUX designers in their quest for voice excellence: Call Tracing.
  Visualizing the Unseen: How Call Tracing Changes the
  Game
  Traditionally, understanding and monitoring voice interaction requires painstaking
  analysis of transcriptions, user feedback, and basic audio playback. Now, Cognigy's
  Call Tracing feature offers an actionable visualization of all activities taking place during
  the call, such as speech recognition and connections, together with the call recording
  waveforms. This powerful tool grants VUX designers an unparalleled view of the
  dynamics of voice interactions
  ```

  3.

  ```markdown theme={null}
  .
  Event and soundwave visualization provides an analytical perspective that goes beyond
  the audio, giving professionals the ability to dissect and understand voice experiences
  at a granular level. It brings critical elements to the forefront that might not be
  immediately evident in transcriptions or basic audio playback.
  ```
</Accordion>

### Example 2: Alternative Chunk Strategy

If you use the Alternative Chunk Strategy, Knowledge AI splits this text into 5 Knowledge Chunks.

Note that in the first Knowledge Chunk, a title is missing because it is formatted as a complex element. In comparison, the [Default Chunk Strategy](#example-1-default-chunk-strategy) recognizes and includes the title in the Knowledge Chunks.

<Accordion title="Alternative Chunk Splitting" defaultOpen="true">
  1.

  ```markdown theme={null}
  In the burgeoning field of voice technology, optimizing Voice User Experience (VUX)
  is a sophisticated endeavor fraught with unique challenges. 
  VUX designers confront intricate variables from timing nuances and intonation accuracy 
  to the unpredictability of human speech and environmental interference.
  ```

  2.

  ```markdown theme={null}
  These factors often present hurdles that can transform an otherwise fluid dialogue
  into a disjointed exchange. 
  For enterprises aiming to scale and perfect their voice-enabled services, 
  these are not mere technicalities but critical pivots on the customer experience journey.
  ```

  3.

  ```markdown theme={null}
  Recognizing this complex landscape, at Cognigy, 
  we're excited to introduce the ultimate tool for developers
  and VUX designers in their quest for voice excellence: Call Tracing.
  ```

  4.

  ```markdown theme={null}
  Traditionally, understanding and monitoring voice interaction requires painstaking analysis of 
  transcriptions, user feedback, and basic audio playback. 
  Now, Cognigy's Call Tracing feature offers an actionable visualization of all activities taking place during the call,
  such as speech recognition and connections, together with the call recording waveforms. 
  This powerful tool grants VUX designers an unparalleled view of the dynamics of voice interactions.
  ```

  5.

  ```markdown theme={null}
  Event and soundwave visualization provides an analytical perspective that goes beyond the audio, 
  giving professionals the ability to dissect and understand voice experiences at a granular level. 
  It brings critical elements to the forefront that might not be 
  immediately evident in transcriptions or basic audio playback.
  ```
</Accordion>

## More Information

* [Knowledge AI Overview](/ai/agents/develop/knowledge-ai/overview)
* [Cognigy Text Format](/ai/agents/develop/knowledge-ai/knowledge-source/text-formats/ctxt)
* [Web Page](/ai/agents/develop/knowledge-ai/knowledge-source/text-formats/web-page)