[FFmpeg-devel] [PATCH v4 2/4] avcodec/jpegxl_parser: add JPEG XL parser

[James Almer]

On 6/26/2023 12:49 PM, Leo Izen wrote:
> +/*
> + * copies as much of the codestream into the buffer as possible
> + * pass a shorter buflen to request less
> + * returns the number of bytes consumed from input, may be greater than input_len
> + * if the input doesn't end on an ISOBMFF-box boundary
> + */
> +int ff_jpegxl_collect_codestream_header(const uint8_t *input_buffer, int input_len,
> +                                        uint8_t *buffer, int buflen, int *copied)
> +{
> +    GetByteContext gb;
> +    int pos = 0;
> +    bytestream2_init(&gb, input_buffer, input_len);
> +
> +    while (1) {
> +        uint64_t size;
> +        uint32_t tag;
> +        int head_size = 8;
> +
> +        if (bytestream2_get_bytes_left(&gb) < 16)
> +            break;
> +
> +        size = bytestream2_get_be32(&gb);
> +        if (size == 1) {
> +            size = bytestream2_get_be64(&gb);
> +            head_size = 16;
> +        }
> +        /* invalid ISOBMFF size */
> +        if (size && size <= head_size)
> +            return AVERROR_INVALIDDATA;

ISOBMFF? Are you propagating container bytes as if they were part of the 
bitstream from image2? Why is it not being handled by the mov/mp4 
demuxer instead?

> +    if (ctx->meta.csp == JPEGXL_CS_GRAY) {
> +        if (ctx->meta.bit_depth <= 8)
> +            avctx->pix_fmt = s->format = ctx->meta.have_alpha ? AV_PIX_FMT_YA8 : AV_PIX_FMT_GRAY8;
> +        else if (ctx->meta.bit_depth <= 16)
> +            avctx->pix_fmt = s->format = ctx->meta.have_alpha ? AV_PIX_FMT_YA16 : AV_PIX_FMT_GRAY16;
> +        else
> +            avctx->pix_fmt = s->format = ctx->meta.have_alpha ? AV_PIX_FMT_NONE : AV_PIX_FMT_GRAYF32;
> +    } else {
> +        if (ctx->meta.bit_depth <= 8)
> +            avctx->pix_fmt = s->format = ctx->meta.have_alpha ? AV_PIX_FMT_RGBA : AV_PIX_FMT_RGB24;
> +        else if (ctx->meta.bit_depth <= 16)
> +            avctx->pix_fmt = s->format = ctx->meta.have_alpha ? AV_PIX_FMT_RGBA64 : AV_PIX_FMT_RGB48;
> +        else
> +            avctx->pix_fmt = s->format = ctx->meta.have_alpha ? AV_PIX_FMT_RGBAF32 : AV_PIX_FMT_RGBF32;

Again, don't fill avctx->pix_fmt, fill s->format.