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[98.224.219.15]) by smtp.gmail.com with ESMTPSA id c15-20020a02c9cf000000b004061056d548sm2055488jap.14.2023.03.16.08.52.25 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Mar 2023 08:52:25 -0700 (PDT) Message-ID: <2f96d225-7555-8d99-1d74-4b551eb9a3b2@gmail.com> Date: Thu, 16 Mar 2023 11:52:25 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Content-Language: en-US-large To: ffmpeg-devel@ffmpeg.org References: <20230308200316.45476-1-leo.izen@gmail.com> <20230308200316.45476-2-leo.izen@gmail.com> From: Leo Izen In-Reply-To: Subject: Re: [FFmpeg-devel] [PATCH v2 1/2] avcodec/pngdec: support sBIT chunks X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: On 3/15/23 21:32, Andreas Rheinhardt wrote: > Leo Izen: >> Add support for reading sBIT chunks, which mark the significant >> bit depth of the PNG file. This passes the metadata using the field >> bits_per_raw_sample of AVCodecContext. >> >> Signed-off-by: Leo Izen >> --- >> libavcodec/pngdec.c | 45 ++++++++++++++++++++++++++++++++++++++++++++ >> libavcodec/version.h | 2 +- >> 2 files changed, 46 insertions(+), 1 deletion(-) >> >> diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c >> index 9403d72f2f..3c91896c9b 100644 >> --- a/libavcodec/pngdec.c >> +++ b/libavcodec/pngdec.c >> @@ -98,6 +98,7 @@ typedef struct PNGDecContext { >> int bpp; >> int has_trns; >> uint8_t transparent_color_be[6]; >> + int significant_bits; >> >> uint32_t palette[256]; >> uint8_t *crow_buf; >> @@ -716,6 +717,14 @@ static int populate_avctx_color_fields(AVCodecContext *avctx, AVFrame *frame) >> avctx->colorspace = frame->colorspace = AVCOL_SPC_RGB; >> avctx->color_range = frame->color_range = AVCOL_RANGE_JPEG; >> >> + /* >> + * tRNS sets alpha depth to full, so we ignore sBIT if set. >> + * As a result we must wait until now to set >> + * avctx->bits_per_raw_sample in case tRNS appears after sBIT >> + */ >> + if (!s->has_trns && s->significant_bits > 0) >> + avctx->bits_per_raw_sample = s->significant_bits; >> + >> return 0; >> } >> >> @@ -996,6 +1005,38 @@ fail: >> return ret; >> } >> >> +static int decode_sbit_chunk(AVCodecContext *avctx, PNGDecContext *s, >> + GetByteContext *gb) >> +{ >> + int bits = 0; >> + int channels; >> + >> + if (!(s->hdr_state & PNG_IHDR)) { >> + av_log(avctx, AV_LOG_ERROR, "sBIT before IHDR\n"); >> + return AVERROR_INVALIDDATA; >> + } >> + >> + if (s->pic_state & PNG_IDAT) { >> + av_log(avctx, AV_LOG_ERROR, "sBIT after IDAT\n"); >> + return AVERROR_INVALIDDATA; >> + } >> + >> + channels = ff_png_get_nb_channels(s->color_type); >> + >> + for (int i = 0; i < channels; i++) { >> + int b = bytestream2_get_byteu(gb); > > What ensures that there is enough input left? > Good catch, I missed a call to bytestream2_get_bytes_left. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".