Software⏱️ 3 min read📅 2026-06-11

How to Fix: FFMpeg Error While Decoding Stream Cannot Allocate Memory

FFmpeg error analysis and metadata for creating a picture-in-picture video from two mp4 videos.

Quick Answer: Use the -c:v libx264 and -g 30 options to improve performance and reduce errors.

📋 Table of Contents

  1. ⚠️ Common Causes
  2. ✅ Best Solutions to Fix It
  3. ✨ Wrapping Up

The error 'Cannot allocate memory' while decoding stream occurs when FFmpeg is unable to allocate sufficient memory to process the video. This issue affects users who are creating picture-in-picture videos from two MP4 files, utilizing GPU acceleration on one machine and not on another.

This error can be frustrating as it prevents the video conversion process from completing successfully. However, in this guide, we will walk through the steps to identify the root causes of this issue and provide solutions for both machines with and without GPUs.

⚠️ Common Causes

  • The primary reason for this error is that FFmpeg is unable to handle the large amount of data required for GPU acceleration. This can be due to various factors such as insufficient video memory, incorrect GPU configuration, or outdated drivers.
  • An alternative reason could be that the input files are too large, causing FFmpeg to run out of memory during processing.

✅ Best Solutions to Fix It

Optimizing Video Settings for GPU Acceleration

  1. Step 1: Step 1: Reduce the resolution of the input videos to decrease the amount of data required for processing. This can be done by using the '-vf' filter option with 'scale' or 'resize' to reduce the video size.
  2. Step 2: Step 2: Increase the video memory settings in FFmpeg by adding the '-mem_limit' option, which allows you to specify a maximum amount of memory that FFmpeg can use. For example, '-mem_limit 1024m'.
  3. Step 3: Step 3: Verify that the GPU drivers are up-to-date and properly configured for FFmpeg. This may involve reinstalling the drivers or adjusting the GPU settings in the system configuration.

Workaround for Machines without GPUs

  1. Step 1: Step 1: Disable GPU acceleration by removing the '-g' option from the command line. For example, 'ffmpeg -itsoffset 1.801 -i 2327_segment_0_remote_0.mp4 -i 2327_segment_0_local_0.mp4 -filter_complex ...'.
  2. Step 2: Step 2: Use software rendering by adding the '-c:v' option with 'libx264' or 'h264' to specify a software-based video codec. For example, '-c:v libx264'.

✨ Wrapping Up

In conclusion, the error 'Cannot allocate memory' while decoding stream can be resolved by optimizing video settings for GPU acceleration on machines with GPUs or using software rendering as a workaround on machines without GPUs.

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