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How to Check What Audio Encoder Settings Were Used When a File Was Created Using ffprobe on the Terminal

This is an article about how to use ffprobe, a command-line utility from the FFmpeg project, to analyze multimedia files and specifically determine the audio encoder settings used when creating an audio file. In this article, you will find information about various aspects of extracting metadata related to audio formats with detailed instructions and examples. Read this article to find out how to identify which audio codec was applied during recording or conversion as well as understanding the quality settings such as bitrate, sample rate, and compression ratio.

Introduction

When dealing with multimedia files like audio recordings or video streams, it’s often necessary to know specific details about their encoding process. For instance, you might want to understand what parameters were used when an audio file was created to ensure consistency in your media management practices. To achieve this goal, ffprobe provides powerful tools that allow for a deep dive into the metadata of multimedia files.

In this article, we’ll cover how to use ffprobe effectively to extract and interpret information related to the encoding settings used on audio files. The focus will be primarily on identifying which audio encoder was utilized (e.g., MP3, AAC, FLAC) along with its specific configuration such as bitrates, sample rates, channel counts, and other relevant parameters.

What is ffprobe?

ffprobe is a command-line tool designed to analyze multimedia files and retrieve metadata associated with them. It’s part of the FFmpeg project, which includes ffmpeg, a versatile utility for converting between different formats. While ffmpeg is used for transforming media files from one format to another, ffprobe serves the purpose of examining these files without altering their content.

Key Features of ffprobe

  • Metadata Retrieval: Extract detailed information about video and audio streams, including codec details, frame rates, bitrates, sample rates, etc.
  • Custom Output Formats: Support for exporting metadata in various formats such as JSON or XML, making it easier to work with the data programmatically.
  • Stream Analysis: Ability to analyze individual media streams within complex multimedia files, providing granular information about each component.

Why Use ffprobe?

Using ffprobe to determine audio encoder settings offers several advantages:

  1. Consistency and Quality Assurance: Ensures that all your media files meet certain quality standards by checking the encoding parameters used.
  2. Diagnostic Tool: Useful for troubleshooting issues related to file playback or format compatibility problems.
  3. Documentation Purposes: Helps in maintaining records of how media assets were encoded, facilitating future reference.

Setting Up ffprobe

Before diving into using ffprobe, ensure you have it installed on your system. On most Linux distributions, FFmpeg (which includes ffprobe) is available through package managers like apt or yum. For macOS and Windows, refer to the official FFmpeg website for installation instructions.

Installation on Ubuntu/Debian

sudo apt update sudo apt install ffmpeg

Installation on macOS (using Homebrew)

brew install ffmpeg

Basic Usage of ffprobe

To start using ffprobe, you need to know its basic syntax. The following command template demonstrates how to use it:

ffprobe [options] input_file

Here, [options] refers to various flags that control the behavior and output format of ffprobe. Some commonly used options include:

  • -v level: Set logging verbosity; levels range from quiet, panic, fatal, error, warning, info, verbose, debug.
  • -print_format fmt: Specify the output format for metadata (e.g., json).
  • -show_format: Show information about the file container.
  • -show_streams: Display details of each stream within a file.

Example Command

To get detailed information about an audio file named example.mp3, use:

ffprobe -v quiet -print_format json -show_format -show_streams example.mp3 > output.json

This command will generate a JSON file (output.json) containing comprehensive metadata of the specified input file.

Extracting Audio Encoder Settings

Now, let’s focus on how to extract specific details about audio encoder settings from an analyzed multimedia file. The primary sections you’ll be interested in are those related to streams and formats.

Analyzing Stream Information

Streams describe individual components within a media container (like video tracks or audio channels). For our purposes, we’re particularly interested in audio streams:

ffprobe -v quiet -print_format json -show_streams input_audio.mp3 > stream_info.json

Inspecting the resulting JSON file will give you insights into various aspects of your audio files, such as:

  • Codec Name: Identifies the codec used (e.g., mp3, aac, flac).
  • Bit Rate Mode: Indicates if the bitrate is constant (CBR) or variable (VBR).
  • Sample Rate: The number of samples per second taken from a continuous signal.
  • Channel Layout: Describes how audio channels are arranged (e.g., stereo, mono).

Example Analysis

Consider an MP3 file with multiple streams:

{ "streams": [ { "index": 0, "codec_name": "mp3", "sample_rate": "44100", "channels": "2" }, ... ] }

From this snippet, you can see that the file contains an MP3 stream with a sample rate of 44.1kHz and stereo (2 channels).

Customizing Output Format

While JSON is commonly used for its structured format, ffprobe offers flexibility in choosing output formats like XML or plain text (default). Here’s how to switch between these options:

  • JSON: Ideal for programmatic processing due to hierarchical structure.

    ffprobe -print_format json ...
  • XML: Another hierarchical format suitable for automated parsing and easy readability.

    ffprobe -print_format xml ...
  • Default (Text): Human-readable plain text output, useful for quick inspections.

    ffprobe -v quiet -show_streams input_audio.mp3

Example Text Output

Using the default format:

ffprobe -v quiet -show_streams input_audio.mp3 Input #0, mp3, from 'input_audio.mp3': Metadata: encoder : Lavf58.29.100 Duration: 00:01:46.27, start: 0.000000, bitrate: 128 kb/s Stream #0:0: Audio: mp3, 44100 Hz, stereo, fltp, 128 kb/s Metadata: encoder : Lavc58.64.100 libmp3lame

This output provides a straightforward view of the audio stream’s properties directly.

Practical Tips for ffprobe

Identifying Specific Encoders

To pinpoint specific codecs, use ffprobe with filters:

ffprobe -v quiet -print_format json -show_streams -select_streams a:0 input_audio.mp3 > single_stream.json

The -select_streams option restricts output to the first audio stream (change a:0 if you have multiple streams).

Filtering Metadata

Sometimes, extensive metadata can be overwhelming. Use JSON path expressions to filter relevant information:

ffprobe -v quiet -print_format json -show_streams input_audio.mp3 | jq '.streams[] | select(.codec_type=="audio")'

This command uses jq, a lightweight and powerful tool for filtering, transforming, and querying JSON data.

Conclusion

Using ffprobe to inspect audio encoder settings not only helps in maintaining quality standards but also ensures efficient media management practices. Whether you’re dealing with MP3 files or other formats, the insights gained from analyzing these details can significantly enhance your workflow by providing a clear understanding of how each file was encoded. By mastering the usage and customization options provided by ffprobe, you’ll be well-equipped to handle various multimedia analysis tasks effectively.

With this comprehensive guide, you now have the tools and knowledge needed to utilize ffprobe efficiently for audio format analysis and beyond.

Last Modified: 25/06/2021 - 16:26:36