On 9/4/20, Andreas Rheinhardt <andreas.rheinha...@gmail.com> wrote:
> YUV4MPEG writes a string as header for both the file itself as well as
> for every frame; these strings contain magic strings and these were up
> until now included in the string to write via %s. Yet they are compile
> time constants, so one can use the compile-time string concatentation
> instead of inserting these strings at runtime.
> Furthermore, the global header has been written via snprintf() to
> a local buffer first before writing it. This can be simplified by using
> avio_printf().
>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@gmail.com>
> ---
lgtm
> That snprintf() call was weird: The buffer used had a size of
> Y4M_LINE_MAX + 1, yet snprintf has been told that the size was
> Y4M_LINE_MAX, despite snprintf always adding a trailing zero (i.e. it
> writes at most Y4M_LINE_MAX - 1 chars and then adds a zero).
> Furthermore, snprintf only returns something negative on format errors,
> not if the buffer is too small (this can be checked via the return
> value). And returning AVERROR(EIO) for this error is strange, too.
>
> libavformat/yuv4mpegenc.c | 21 +++++++--------------
> 1 file changed, 7 insertions(+), 14 deletions(-)
>
> diff --git a/libavformat/yuv4mpegenc.c b/libavformat/yuv4mpegenc.c
> index c4781042bd..fdd020e13b 100644
> --- a/libavformat/yuv4mpegenc.c
> +++ b/libavformat/yuv4mpegenc.c
> @@ -24,18 +24,15 @@
> #include "internal.h"
> #include "yuv4mpeg.h"
>
> -#define Y4M_LINE_MAX 256
> -
> static int yuv4_write_header(AVFormatContext *s)
> {
> AVStream *st;
> AVIOContext *pb = s->pb;
> int width, height;
> - int raten, rated, aspectn, aspectd, n;
> + int raten, rated, aspectn, aspectd, ret;
> char inter;
> const char *colorspace = "";
> const char *colorrange = "";
> - char buf[Y4M_LINE_MAX + 1];
> int field_order;
>
> st = s->streams[0];
> @@ -170,19 +167,15 @@ static int yuv4_write_header(AVFormatContext *s)
> break;
> }
>
> - /* construct stream header, if this is the first frame */
> - n = snprintf(buf, Y4M_LINE_MAX, "%s W%d H%d F%d:%d I%c A%d:%d%s%s\n",
> - Y4M_MAGIC, width, height, raten, rated, inter,
> - aspectn, aspectd, colorspace, colorrange);
> -
> - if (n < 0) {
> + ret = avio_printf(pb, Y4M_MAGIC " W%d H%d F%d:%d I%c A%d:%d%s%s\n",
> + width, height, raten, rated, inter,
> + aspectn, aspectd, colorspace, colorrange);
> + if (ret < 0) {
> av_log(s, AV_LOG_ERROR,
> "Error. YUV4MPEG stream header write failed.\n");
> - return AVERROR(EIO);
> + return ret;
> }
>
> - avio_write(pb, buf, strlen(buf));
> -
> return 0;
> }
>
> @@ -200,7 +193,7 @@ static int yuv4_write_packet(AVFormatContext *s,
> AVPacket *pkt)
>
> /* construct frame header */
>
> - avio_printf(s->pb, "%s\n", Y4M_FRAME_MAGIC);
> + avio_printf(s->pb, Y4M_FRAME_MAGIC "\n");
>
> width = st->codecpar->width;
> height = st->codecpar->height;
> --
> 2.20.1
>
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