# Failed to load KTX2 texture data: Error: KTX2 container - could not transcode the data. TypeError: Cannot convert "undefined" to unsigned int **URL:** \ **Category:** Bugs\ **Tags:** texture, ktx2\ **Created:** [March 3, 2023, 9:15pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726 "2023-03-03T21:15:56Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![Jon\_Jekeli](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/jon_jekeli/32/1697_2.png) [@Jon\_Jekeli](https://forum.babylonjs.com/u/Jon_Jekeli)\ **Post date:** [March 3, 2023, 9:15pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/1 "2023-03-03T21:15:56Z")
Hi, we are getting an error with our textures that we converted to KTX2. See warnings in playground here: [https://playground.babylonjs.com/#20OAV9#10002](https://playground.babylonjs.com/#20OAV9#10002). We are converting the KTX2 files using the khronos provided converters. Our python code looks like: ```auto # Convert to KTX2 tempName = os.path.splitext(filePath)[0] + '-uncompressed.ktx2' procresult = subprocess.run(['toktx', '--t2', tempName, filePath], stdout=subprocess.PIPE, stderr=subprocess.PIPE) checkProcType(procresult, "Error converting texture (KTX2) (OUT: " + tempName + ") : (IN: " + filePath + ")") newName = os.path.splitext(filePath)[0] + '.ktx2' # Supercompress KTX2 procresult = subprocess.run(['ktxsc', '-zcmp', '-o', newName, tempName], stdout=subprocess.PIPE, stderr=subprocess.PIPE) ``` Any ideas on what may be happening or what that error is telling us? ---
**Author:** ![Jon\_Jekeli](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/jon_jekeli/32/1697_2.png) [@Jon\_Jekeli](https://forum.babylonjs.com/u/Jon_Jekeli)\ **Post date:** [March 3, 2023, 9:19pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/2 "2023-03-03T21:19:09Z")
We even used the ktx2 checker provided by khronos and it reports it as a valid ktx2 file. Side note, we’re 90% certain this worked several weeks ago, so no sure if anything has changed with the transcoder in the last few weeks. ---
**Author:** ![sebavan](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/sebavan/32/57_2.png) [@sebavan](https://forum.babylonjs.com/u/sebavan)\ **Post date:** [March 3, 2023, 9:19pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/3 "2023-03-03T21:19:39Z")
@bghgary @Evgeni_Popov any ideas what could it be ? ---
**Author:** ![JCPalmer](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/jcpalmer/32/42_2.png) [@JCPalmer](https://forum.babylonjs.com/u/JCPalmer)\ **Post date:** [March 4, 2023, 12:32pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/4 "2023-03-04T12:32:37Z")
Sorry to hijack your topic, but i was looking into a way to make ktx2 conversion part of the Blender exporter. All i had seen was C based code. While i had previously made a DLL for Blender to directly connect a Kinect 2 motion capture device, that seems inferior to a Python based system. Where did you get it? ---
**Author:** ![Jon\_Jekeli](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/jon_jekeli/32/1697_2.png) [@Jon\_Jekeli](https://forum.babylonjs.com/u/Jon_Jekeli)\ **Post date:** [March 4, 2023, 2:30pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/5 "2023-03-04T14:30:45Z")
Just something we wrote. Not a blender plugin or anything, part of a larger texture conversion system that takes in pngs and spits out a variety of image formats in different LODs. ---
**Author:** ![Evgeni\_Popov](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/evgeni_popov/32/4432_2.png) [@Evgeni\_Popov](https://forum.babylonjs.com/u/Evgeni_Popov)\ **Post date:** [March 4, 2023, 3:38pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/6 "2023-03-04T15:38:20Z")
---
**Author:** ![Evgeni\_Popov](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/evgeni_popov/32/4432_2.png) [@Evgeni\_Popov](https://forum.babylonjs.com/u/Evgeni_Popov)\ **Post date:** [March 4, 2023, 3:40pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/7 "2023-03-04T15:40:45Z")
We don’t support R8G8B8 SRGB in the KTX2 decoder, try R8G8B8A8 SRGB instead. ---
**Author:** ![Jon\_Jekeli](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/jon_jekeli/32/1697_2.png) [@Jon\_Jekeli](https://forum.babylonjs.com/u/Jon_Jekeli)\ **Post date:** [March 4, 2023, 6:38pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/8 "2023-03-04T18:38:06Z")
Will give that a try monday and report back! Thank you! Is any of the ktx2 requirements for babylonjs documented anywhere? ---
**Author:** ![RPaladin](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/rpaladin/32/27367_2.png) [@RPaladin](https://forum.babylonjs.com/u/RPaladin)\ **Post date:** [March 4, 2023, 8:08pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/9 "2023-03-04T20:08:36Z")
Here are all of the supported KTX2 decoder types for Babylon.js: > > > //github.com/BabylonJS/Babylon.js/tree/master/packages/tools/ktx2Decoder/src/Transcoders Here is also a list of supported formats for KTX texture containers for WebGL: > **[Multi-Platform Compressed Textures | Babylon.js Documentation](https://doc.babylonjs.com/features/featuresDeepDive/materials/advanced/mutliPlatTextures#khronos-texture-container-format-ktx-files)** > > Learn all about multi-platform compressed textures in Babylon.js. * * * Unrelated, for those unsure what the differences are between KTX and KTX2, here’s a good summary: > [@KTX vs KTX2 format](https://forum.babylonjs.com/t/ktx-vs-ktx2-format/37502/2): > > KTX2(and .basis) have this “Universal supercompression” Meaning that once downloaded, a worker thread transcodes them to a real compression format. Meaning it picks the optimal format for the hardware the person is viewing with and that is what’s sent back to main thread The first article is talking about device specific the ‘older’ way. Which is you offline generate a version of a texture for each different CPU (mytex-astc.ktx, mytex-etc2.ktx, mytex-pvrtc.ktx etc etc ). Babylon for instance t… ---
**Author:** ![Jon\_Jekeli](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/jon_jekeli/32/1697_2.png) [@Jon\_Jekeli](https://forum.babylonjs.com/u/Jon_Jekeli)\ **Post date:** [March 5, 2023, 12:39am UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/10 "2023-03-05T00:39:09Z")
Still failing, see [https://playground.babylonjs.com/#20OAV9#10015](https://playground.babylonjs.com/#20OAV9#10015) (only the first texture was converted to R8G8B8A8 SRGB ([https://storage.googleapis.com/vcassets/production/vcn/var/000006/0000786f/Texture/1025.ktx2](https://storage.googleapis.com/vcassets/production/vcn/var/000006/0000786f/Texture/1025.ktx2)). New code to transform is ```auto toktx --t2 --target_type RGBA test-uncompressed.ktx2 1024.png ktxsc -zcmp -o 1025.ktx2 test-uncompressed.ktx2 ``` Attached the KTX info as well: ```auto ktxinfo 1025.ktx2 Header identifier: «KTX 20»\r\n\x1A\n vkFormat: VK_FORMAT_R8G8B8A8_SRGB typeSize: 1 pixelWidth: 1024 pixelHeight: 1024 pixelDepth: 0 layerCount: 0 faceCount: 1 levelCount: 1 supercompressionScheme: KTX_SS_ZSTD dataFormatDescriptor.byteOffset: 0x68 dataFormatDescriptor.byteLength: 92 keyValueData.byteOffset: 0xc4 keyValueData.byteLength: 108 supercompressionGlobalData.byteOffset: 0 supercompressionGlobalData.byteLength: 0 Level Index Level0.byteOffset: 0x130 Level0.byteLength: 376387 Level0.uncompressedByteLength: 4194304 Data Format Descriptor DFD total bytes: 92 BDB descriptor type 0x0000 vendor id = 0x00000 Descriptor block size 88 (4 samples) versionNumber = 0x0002 Flags 0x00 Xfer 02 Primaries 01 Model 001 Dimensions: 1,1,1,1 Plane bytes: 0,0,0,0,0,0,0,0 Sample 0 Qualifiers 0 Channel 0x0 (R) Length 8 bits Offset 0 Position: 0,0,0,0 Lower 0x00000000 Upper 0x000000ff Sample 1 Qualifiers 0 Channel 0x1 (G) Length 8 bits Offset 8 Position: 0,0,0,0 Lower 0x00000000 Upper 0x000000ff Sample 2 Qualifiers 0 Channel 0x2 (B) Length 8 bits Offset 16 Position: 0,0,0,0 Lower 0x00000000 Upper 0x000000ff Sample 3 Qualifiers 1 Channel 0xf (A) Length 8 bits Offset 24 Position: 0,0,0,0 Lower 0x00000000 Upper 0x000000ff Key/Value Data KTXorientation: rd KTXwriter: ktxsc v4.0.0-beta6~6 / libktx v4.0.0~5 KTXwriterScParams: -zcmp ``` ---
**Author:** ![Evgeni\_Popov](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/evgeni_popov/32/4432_2.png) [@Evgeni\_Popov](https://forum.babylonjs.com/u/Evgeni_Popov)\ **Post date:** [March 5, 2023, 8:26pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/11 "2023-03-05T20:26:40Z")
The current code for the MSC transcoder module needs that `supercompressionGlobalData` have non empty data to work in the `ETC1S` case. I will have to see if we can do something about it. ---
**Author:** ![Evgeni\_Popov](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/evgeni_popov/32/4432_2.png) [@Evgeni\_Popov](https://forum.babylonjs.com/u/Evgeni_Popov)\ **Post date:** [March 6, 2023, 11:23am UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/12 "2023-03-06T11:23:35Z")
It seems that not specifying an encoding scheme with `ktxsc` will generate a **ETC1S** encoded file. But Zstandard compression (`--zcmp`) is not supported for **ETC1S**. Excerpt from `ktxsc -h`: ```auto --zcmp [] Supercompress the data with Zstandard. Implies --t2. Can be used with data in any format except ETC1S / BasisLZ. Most effective with RDO-conditioned UASTC or uncompressed formats. The optional compressionLevel range is 1 - 22 and the default is 3. Lower values=faster but give less compression. Values above 20 should be used with caution as they require more memory. ``` So, you should either use **UASTC** if you want to compress with Zstandard, or select the **ETC1S** compression scheme: - ktxsc --encode uastc --zcmp -o 1025.ktx2 test-uncompressed.ktx2 - ktxsc --encode etc1s -o 1025.ktx2 test-uncompressed.ktx2 ---
**Author:** ![Jon\_Jekeli](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/jon_jekeli/32/1697_2.png) [@Jon\_Jekeli](https://forum.babylonjs.com/u/Jon_Jekeli)\ **Post date:** [March 6, 2023, 3:11pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/13 "2023-03-06T15:11:45Z")
This was it!! Quick question on the compressionLevel. Is “speed” affect the speed of de-compression at runtime? or only the speed of the conversion to initially compress it. Because we dont care about the speed of compression, but we absolutely care about decompression. ---
**Author:** ![Jon\_Jekeli](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/jon_jekeli/32/1697_2.png) [@Jon\_Jekeli](https://forum.babylonjs.com/u/Jon_Jekeli)\ **Post date:** [March 6, 2023, 3:16pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/14 "2023-03-06T15:16:05Z")
Also for anyone coming along with same problem, we were able to change back to RGB instead of RGBA and have it still work. Was just the ESTC1S vs UASTC ---
**Author:** ![Evgeni\_Popov](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/evgeni_popov/32/4432_2.png) [@Evgeni\_Popov](https://forum.babylonjs.com/u/Evgeni_Popov)\ **Post date:** [March 6, 2023, 5:32pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/15 "2023-03-06T17:32:34Z")
> [@Jon\_Jekeli](#): > > This was it!! Quick question on the compressionLevel. Is “speed” affect the speed of de-compression at runtime? or only the speed of the conversion to initially compress it In my understanding, the compression level affects the speed only at the compression stage. ---
**Author:** ![Jon\_Jekeli](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/jon_jekeli/32/1697_2.png) [@Jon\_Jekeli](https://forum.babylonjs.com/u/Jon_Jekeli)\ **Post date:** [March 6, 2023, 5:51pm UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/16 "2023-03-06T17:51:21Z")
> [@Evgeni\_Popov](#): > > In my understanding, the compression level affects the speed only at the compression stage. Thanks! ---
**Author:** ![Evgeni\_Popov](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/evgeni_popov/32/4432_2.png) [@Evgeni\_Popov](https://forum.babylonjs.com/u/Evgeni_Popov)\ **Post date:** [March 8, 2023, 10:08am UTC](https://forum.babylonjs.com/t/failed-to-load-ktx2-texture-data-error-ktx2-container-could-not-transcode-the-data-typeerror-cannot-convert-undefined-to-unsigned-int/38726/17 "2023-03-08T10:08:23Z")