Convert MP4 to AVI

As it is or High: the choice that matters

AVI can hold H.264, the codec inside almost every MP4. With As it is, Octoolo takes that shortcut and copies the MP4's H.264 picture into the AVI unchanged. The result plays in VLC and on most computers, but most players from the DivX era cannot decode H.264, and they typically show nothing or refuse the file.

For those players, pick High, Balanced or Small. The picture is then encoded as MPEG-4 Part 2, the codec Xvid and DivX use, and tagged XVID so players recognize it. AAC sound, which most MP4s have, becomes MP3 either way, since AVI players do not expect AAC.

The rule of thumb: As it is for a PC program that just wants the .avi ending, High for anything with a disc tray or a DivX logo.

Settings for DivX and Xvid players

Players with a DivX or Xvid logo were mostly designed for DVD-sized video. If an AVI plays with stutter or not at all, the picture size is the first thing to lower:

• Size: 480p brings HD video down to standard definition. Octoolo keeps the shape, so a wide video stays wide; if it still will not play, try 360p.
• Frames a second: As it is for most videos. If the MP4 runs at 50 or 60 frames a second, try 25 or 30.
• One sound track. AVI keeps the first sound track of the MP4; other languages are left out.
• No subtitles. They are not carried into the AVI.

Test one file on the player before converting a whole folder. Once it plays, drop the folder and let the batch run.

Why the AVI is bigger

Xvid is MPEG-4 Part 2, an older codec than H.264, and it needs more bits for the same picture. Octoolo budgets about one and a half times as many bits for it as for H.264, so at High an AVI usually outweighs the MP4 it was made from. Balanced and Small bring the size down, as does a smaller picture, which an old player may need anyway.

Xvid is encoded on the processor, not the graphics card, and Octoolo converts one video at a time, with each line showing its progress and the time left. A folder of long videos is a good job to start before a break. If you need to stop, Stop all ends the batch, and a stopped file leaves nothing half-made behind.

Other reasons to want AVI

Beyond disc players, AVI is still asked for by older Windows programs and editors that do not import MP4. If a program's import dialog lists AVI and not MP4, this is the conversion for it, and As it is may be all it takes. Try that first, since a copy is quick and loses nothing; if the program then complains about the video, convert again at High.

It also suits a collection kept in one form. If an archive of family videos has been Xvid AVI for years, new clips can join it in the same format and play in the same players. Going the other way, from an old AVI collection to files phones and TVs play, is AVI to MP4. For programs built around Windows Media instead, see MP4 to WMV.