feat: Support for video-to-animated-image conversion with frame sampling #273
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Enables extraction of multiple frames from video sources (MP4, MOV, WEBM) at configurable sample intervals to produce animated image outputs (animated WebP, GIF). Introduces VideoFrameSampleInterval option to control frame sampling rate and extends decoder with VideoDecoder interface for multi-frame extraction. Also improves memory alignment handling for better SIMD performance.
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| package lilliput | |||
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I'm seeing there are third party libs like "testify" that can provide more idiomatic asserts, but given our direction with go it's probably not in scope. Just noting.
| return h.contentLength | ||
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| // calculateAlignedStride computes a 32-byte aligned stride for the given width and channel count. |
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I'm used to seeing a function called to detect the actual memory alignment requirements of the platform.
32 byte alignment will probably work but isn't strictly correct unless we explicitly assume the data type is 8 bits per pixel, plus the buffer should be allocated with some sort of aligned malloc function.
Maybe we add some sort of comment re: the platforms we're expecting this function to work with or have tested with otherwise.
avcodec.cpp
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| int video_stream_index; | ||
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| // Multi-frame extraction state | ||
| float frame_sample_interval; // Interval between frames in seconds |
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my instinct is to use integers for exact precision unless there's a specific need for floats.
| int delay_ms = (int)(delay_seconds * 1000.0); | ||
| // Validate delay is reasonable (between 1ms and 60 seconds) | ||
| // Use sample interval if delay is out of bounds | ||
| if (delay_ms > 0 && delay_ms <= 60000) { |
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is this the output delay per frame? if so arguably 1ms is pretty low. What's a reasonable default?
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Good point, yeah, in practice we'll use something like 100-200ms. I don't think we want to have a default since the feature is enabled by specifying a positive non-zero value.
Change VideoFrameSampleInterval from float64 seconds to int milliseconds across the codebase. This provides more precision and clearer semantics for frame sampling intervals. - Update avcodec decoder to track frame_sample_interval_ms as int - Update Go API to use VideoFrameSampleIntervalMs int - Update all test cases to use millisecond values - Fix outdated documentation comments
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Enables extraction of multiple frames from video sources (MP4, MOV, WEBM) at configurable sample intervals to produce animated image outputs (animated WebP, GIF). Introduces VideoFrameSampleInterval option to control frame sampling rate and extends decoder with VideoDecoder interface for multi-frame extraction. Also improves memory alignment handling for better SIMD performance.