Use a different file format

Oct 13, 2025 by leolavanderia.com.br 30 views

Introduction

When working with video files, especially those encoded in HEVC (High Efficiency Video Coding) format, errors can occur during analysis. One such error is the "failed parsing h256 nal-header" error, which can be frustrating to resolve. In this article, we will delve into the details of this error, explore possible causes, and provide a step-by-step guide to troubleshoot and potentially fix the issue.

Understanding NAL-Header

Before we dive into the error, let's briefly explain what a NAL (Network Abstraction Layer) header is. A NAL header is a metadata structure that accompanies video and audio data in a compressed video file. It contains information about the compressed data, such as the type of data, the size of the data, and the timestamp of the data. The NAL header is essential for decoding the compressed data and reconstructing the original video and audio streams.

The Error: Failed Parsing H.256 NAL-Header

The error "failed parsing h256 nal-header" indicates that the FFmpeg library, which is used for video and audio processing, is unable to parse the NAL header of a HEVC video file. This error can occur due to various reasons, including:

Corrupted video file: The video file may be corrupted due to a power failure, disk error, or other issues.
Incorrect file format: The video file may be in an incorrect format, such as MP4, which is not compatible with the FFmpeg library.
Incompatible codec: The video file may be encoded with a codec that is not supported by the FFmpeg library.

Analyzing the Logs

The provided logs contain valuable information that can help us troubleshoot the issue. Let's break down the key points from the logs:

NAL type: The NAL type is 1, which indicates that the NAL header is a slice header.
nuh_layer_id: The nuh_layer_id is 0, which indicates that the NAL header is a top-level slice header.
nuh_temporal_id_plus1: The nuh_temporal_id_plus1 is 1, which indicates that the NAL header is a single slice header.
first_slice_segment_in_pic_flag: The first_slice_segment_in_pic_flag is 1, which indicates that the NAL header is the first slice segment in a picture.
Partial hvc1-length: The partial hvc1-length is 33307, which indicates that the NAL header is a partial slice header.
detected size: The detected size is 33307, which indicates that the NAL header is a valid slice header.

Troubleshooting Steps

Based on the analysis of the logs, we can try the following troubleshooting steps to resolve the issue:

Verify the video file: Check the video file for any signs of corruption or damage. If the file is corrupted, try to recover it using a data recovery tool.
Check the file format: Verify that the video file is in a compatible format, such as MP4 or MKV. If the file is in an incompatible format, try to convert it to a compatible format.
Check the codec: Verify that the video file is encoded with a compatible codec, such as HEVC. If the file is encoded with an incompatible codec, try to re-encode it with a compatible codec.
Use the -sv option: Try using the -sv option with FFmpeg to enable the "slice segment" mode, which can help to recover corrupted video files.
Use the untrunc tool: Try using the untrunc tool to recover the video file. This tool can help to remove any corrupted or damaged data from the file.

Conclusion

In conclusion, the "failed parsing h256 nal-header" error can be a frustrating issue to resolve, but by analyzing the logs and following the troubleshooting steps outlined in this article, we can potentially fix the issue. Remember to always verify the video file for any signs of corruption or damage, check the file format and codec, and try using the -sv option and untrunc tool to recover the video file.

Additional Information

If you are experiencing issues with HEVC/MP4 video files, you can try the following:

Use a different codec: Try encoding the video file with a different codec, such as H.264 or VP9.
Use a different file format: Try encoding the video file in a different format, such as MKV or AVI.
Use a different FFmpeg version: Try using a different version of FFmpeg, such as FFmpeg 4.2 or later.

Sample Video

If you are willing to provide a sample video, please provide a link to the video file or a description of the video file, including the codec, file format, and any other relevant information.

FFmpeg Version

Q: What is a NAL header, and why is it important?

A: A NAL (Network Abstraction Layer) header is a metadata structure that accompanies video and audio data in a compressed video file. It contains information about the compressed data, such as the type of data, the size of the data, and the timestamp of the data. The NAL header is essential for decoding the compressed data and reconstructing the original video and audio streams.

Q: What is the difference between a NAL header and a slice header?

A: A NAL header is a metadata structure that accompanies video and audio data in a compressed video file, while a slice header is a specific type of NAL header that contains information about a single slice of video data. A slice header is typically used to indicate the start of a new slice of video data.

Q: What is the purpose of the nuh_layer_id field in a NAL header?

A: The nuh_layer_id field in a NAL header is used to indicate the layer ID of the NAL unit. The layer ID is a value that is used to identify the layer of the video data that the NAL unit belongs to.

Q: What is the purpose of the first_slice_segment_in_pic_flag field in a NAL header?

A: The first_slice_segment_in_pic_flag field in a NAL header is used to indicate whether the NAL unit is the first slice segment in a picture. This flag is used to help the decoder determine the correct order of the slice segments in a picture.

Q: What is the difference between a partial hvc1-length and a full hvc1-length?

A: A partial hvc1-length is a value that indicates the length of a partial slice header, while a full hvc1-length is a value that indicates the length of a full slice header. A partial slice header is a slice header that contains only a portion of the information required to decode a slice of video data.

Q: What is the purpose of the detected size field in a NAL header?

A: The detected size field in a NAL header is used to indicate the size of the NAL unit. This field is used to help the decoder determine the correct size of the NAL unit.

Q: What is the difference between a valid slice header and an invalid slice header?

A: A valid slice header is a slice header that contains all the necessary information required to decode a slice of video data, while an invalid slice header is a slice header that is missing some or all of the necessary information.

Q: What is the purpose of the -sv option in FFmpeg?

A: The -sv option in FFmpeg is used to enable the "slice segment" mode, which can help to recover corrupted video files.

Q: What is the purpose of the untrunc tool?

A: The untrunc tool is used to recover corrupted video files by removing any damaged or corrupted data from the file.

Q: What are some common causes of the "failed parsing h256 nal-header" error?

A: Some common causes of the "failed parsing h256 nal-header" error include:

Corrupted video file
Incorrect file format
Incompatible codec
Incorrect FFmpeg version

Q: How can I troubleshoot the "failed parsing h256 nal-header" error?

A: To troubleshoot the "failed parsing h256 nal-header" error, you can try the following:

Verify the video file for any signs of corruption or damage
Check the file format and codec
Try using the -sv option and untrunc tool
Use a different FFmpeg version

Q: What are some best practices for working with HEVC/MP4 video files?

A: Some best practices for working with HEVC/MP4 video files include:

Verifying the video file for any signs of corruption or damage
Checking the file format and codec
Using a compatible FFmpeg version
Using a different codec or file format if necessary
Using a data recovery tool if the file is corrupted.