| Message ID | 20240130144608.54492-1-leo.izen@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel,v2] avcodec/libjxlenc: support negative linesizes | expand |
| Context | Check | Description |
|---|---|---|
| yinshiyou/make_loongarch64 | success | Make finished |
| yinshiyou/make_fate_loongarch64 | success | Make fate finished |
| andriy/make_x86 | success | Make finished |
| andriy/make_fate_x86 | success | Make fate finished |
On 1/30/24 09:46, Leo Izen wrote: > libjxl doesn't support negative strides, but JPEG XL has an orientation > flag inside the codestream. We can use this to work around the library > limitation, by taking the absolute value of the negative row stride, > sending the image up-side-down, and telling the library that the image > has a vertical-flip orientation. > > Signed-off-by: Leo Izen <leo.izen@gmail.com> > --- Changes from v1: - constify uint8_t *data, per Andreas's request
Leo Izen: > libjxl doesn't support negative strides, but JPEG XL has an orientation > flag inside the codestream. We can use this to work around the library > limitation, by taking the absolute value of the negative row stride, > sending the image up-side-down, and telling the library that the image > has a vertical-flip orientation. > > Signed-off-by: Leo Izen <leo.izen@gmail.com> > --- > libavcodec/libjxlenc.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/libavcodec/libjxlenc.c b/libavcodec/libjxlenc.c > index 67be8a01ca..4ddd5f9f2c 100644 > --- a/libavcodec/libjxlenc.c > +++ b/libavcodec/libjxlenc.c > @@ -259,6 +259,7 @@ static int libjxl_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFra > size_t available = ctx->buffer_size; > size_t bytes_written = 0; > uint8_t *next_out = ctx->buffer; > + const uint8_t *data; > > ret = libjxl_init_jxl_encoder(avctx); > if (ret) { > @@ -303,6 +304,7 @@ static int libjxl_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFra > > /* bitexact lossless requires there to be no XYB transform */ > info.uses_original_profile = ctx->distance == 0.0; > + info.orientation = frame->linesize[0] >= 0 ? JXL_ORIENT_IDENTITY : JXL_ORIENT_FLIP_VERTICAL; > > if (JxlEncoderSetBasicInfo(ctx->encoder, &info) != JXL_ENC_SUCCESS) { > av_log(avctx, AV_LOG_ERROR, "Failed to set JxlBasicInfo\n"); > @@ -383,9 +385,15 @@ static int libjxl_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFra > } > > jxl_fmt.endianness = JXL_NATIVE_ENDIAN; > - jxl_fmt.align = frame->linesize[0]; > + if (frame->linesize[0] >= 0) { > + jxl_fmt.align = frame->linesize[0]; > + data = frame->data[0]; > + } else { > + jxl_fmt.align = -frame->linesize[0]; > + data = frame->data[0] - jxl_fmt.align * (info.ysize - 1); Please don't rely on the type of jxl_fmt.align here (which is out of our control). E.g. in the future it may be that libjxl supports only 32bit align values (i.e. uses uint32_t or so for it), but that we support 64bit (ptrdiff_t) linesizes and allocations, so that jxl_fmt.align * (info.ysize - 1) may overflow this even when -linesize fits into jxl_fmt.align. (Very unlikely given that align is size_t and they will likely not go back from this, but it could happen.) > + } > > - if (JxlEncoderAddImageFrame(ctx->options, &jxl_fmt, frame->data[0], jxl_fmt.align * info.ysize) != JXL_ENC_SUCCESS) { > + if (JxlEncoderAddImageFrame(ctx->options, &jxl_fmt, data, jxl_fmt.align * info.ysize) != JXL_ENC_SUCCESS) { > av_log(avctx, AV_LOG_ERROR, "Failed to add Image Frame\n"); > return AVERROR_EXTERNAL; > }
On 1/30/24 09:57, Andreas Rheinhardt wrote: > > Please don't rely on the type of jxl_fmt.align here (which is out of our > control). E.g. in the future it may be that libjxl supports only 32bit > align values (i.e. uses uint32_t or so for it), but that we support > 64bit (ptrdiff_t) linesizes and allocations, so that jxl_fmt.align * > (info.ysize - 1) may overflow this even when -linesize fits into > jxl_fmt.align. > (Very unlikely given that align is size_t and they will likely not go > back from this, but it could happen.) > This would be an ABI break though, wouldn't it? Why do we need to work around a potential future ABI break?
On 1/30/2024 12:06 PM, Leo Izen wrote: > On 1/30/24 09:57, Andreas Rheinhardt wrote: >> >> Please don't rely on the type of jxl_fmt.align here (which is out of our >> control). E.g. in the future it may be that libjxl supports only 32bit >> align values (i.e. uses uint32_t or so for it), but that we support >> 64bit (ptrdiff_t) linesizes and allocations, so that jxl_fmt.align * >> (info.ysize - 1) may overflow this even when -linesize fits into >> jxl_fmt.align. >> (Very unlikely given that align is size_t and they will likely not go >> back from this, but it could happen.) >> > > This would be an ABI break though, wouldn't it? Why do we need to work > around a potential future ABI break? Point is, we have control over frame->linesize[0], but not over jxl_fmt.align, so the former is better to calculate offsets in our code.
diff --git a/libavcodec/libjxlenc.c b/libavcodec/libjxlenc.c index 67be8a01ca..4ddd5f9f2c 100644 --- a/libavcodec/libjxlenc.c +++ b/libavcodec/libjxlenc.c @@ -259,6 +259,7 @@ static int libjxl_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFra size_t available = ctx->buffer_size; size_t bytes_written = 0; uint8_t *next_out = ctx->buffer; + const uint8_t *data; ret = libjxl_init_jxl_encoder(avctx); if (ret) { @@ -303,6 +304,7 @@ static int libjxl_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFra /* bitexact lossless requires there to be no XYB transform */ info.uses_original_profile = ctx->distance == 0.0; + info.orientation = frame->linesize[0] >= 0 ? JXL_ORIENT_IDENTITY : JXL_ORIENT_FLIP_VERTICAL; if (JxlEncoderSetBasicInfo(ctx->encoder, &info) != JXL_ENC_SUCCESS) { av_log(avctx, AV_LOG_ERROR, "Failed to set JxlBasicInfo\n"); @@ -383,9 +385,15 @@ static int libjxl_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFra } jxl_fmt.endianness = JXL_NATIVE_ENDIAN; - jxl_fmt.align = frame->linesize[0]; + if (frame->linesize[0] >= 0) { + jxl_fmt.align = frame->linesize[0]; + data = frame->data[0]; + } else { + jxl_fmt.align = -frame->linesize[0]; + data = frame->data[0] - jxl_fmt.align * (info.ysize - 1); + } - if (JxlEncoderAddImageFrame(ctx->options, &jxl_fmt, frame->data[0], jxl_fmt.align * info.ysize) != JXL_ENC_SUCCESS) { + if (JxlEncoderAddImageFrame(ctx->options, &jxl_fmt, data, jxl_fmt.align * info.ysize) != JXL_ENC_SUCCESS) { av_log(avctx, AV_LOG_ERROR, "Failed to add Image Frame\n"); return AVERROR_EXTERNAL; }
libjxl doesn't support negative strides, but JPEG XL has an orientation flag inside the codestream. We can use this to work around the library limitation, by taking the absolute value of the negative row stride, sending the image up-side-down, and telling the library that the image has a vertical-flip orientation. Signed-off-by: Leo Izen <leo.izen@gmail.com> --- libavcodec/libjxlenc.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)