MKVmerge

[Numerique]

Hi at all!
Either a large ".mkv" files (1920 * 1080, h264 and e-ac3) in which 6mn have been removed. The two remaining files were successively encoded with Handbrake (same parameters).
Problem: "mkvmerge" adds the sound part of the second file to the first but not the video (random pixels). mkvmerge talks about same length codec error (47) but not with same content. Identical result on command line or with mkvmergegui. mkvinfo gives the same codec for both files (V_MPEG4/ISO/AVC) ... Anyone have any idea of the problem ???
Thank you so much.

[Woodstock]

MKVmerge defaults to combining the files, but there is the option to APPEND the files. Which did you chose?

[Numerique]

Hello...
My choice: concatenate. The soundtrack added to the first file is ok but the added video is reported in error and in random pixels.
Thank you very much for your intervention.

[Numerique]

Hello...
Problem solved: To concatenate two ".mkv" files encoded with the same parameters you must use "avidemux". Immediate result.
Thank you