[FFmpeg-devel] [PATCH] avformat/rtpdec: Avoid allocations of small dynamic buffers

[Andreas Rheinhardt]

Andreas Rheinhardt:
> Besides avoiding allocations this also fixes a design defect of
> ff_rtp_send_punch_packets: It did not return an error in case of
> these allocations failed.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
>  libavformat/rtpdec.c | 38 +++++++++++++-------------------------
>  1 file changed, 13 insertions(+), 25 deletions(-)
> 
> diff --git a/libavformat/rtpdec.c b/libavformat/rtpdec.c
> index f40c020c33..d592e34893 100644
> --- a/libavformat/rtpdec.c
> +++ b/libavformat/rtpdec.c
> @@ -404,38 +404,26 @@ int ff_rtp_check_and_send_back_rr(RTPDemuxContext *s, URLContext *fd,
>  
>  void ff_rtp_send_punch_packets(URLContext *rtp_handle)
>  {
> -    AVIOContext *pb;
> -    uint8_t *buf;
> -    int len;
> +    uint8_t buf[RTP_MIN_PACKET_LENGTH], *ptr = buf;
>  
>      /* Send a small RTP packet */
> -    if (avio_open_dyn_buf(&pb) < 0)
> -        return;
>  
> -    avio_w8(pb, (RTP_VERSION << 6));
> -    avio_w8(pb, 0); /* Payload type */
> -    avio_wb16(pb, 0); /* Seq */
> -    avio_wb32(pb, 0); /* Timestamp */
> -    avio_wb32(pb, 0); /* SSRC */
> +    bytestream_put_byte(&ptr, (RTP_VERSION << 6));
> +    bytestream_put_byte(&ptr, 0); /* Payload type */
> +    bytestream_put_be16(&ptr, 0); /* Seq */
> +    bytestream_put_be32(&ptr, 0); /* Timestamp */
> +    bytestream_put_be32(&ptr, 0); /* SSRC */
>  
> -    len = avio_close_dyn_buf(pb, &buf);
> -    if ((len > 0) && buf)
> -        ffurl_write(rtp_handle, buf, len);
> -    av_free(buf);
> +    ffurl_write(rtp_handle, buf, ptr - buf);
>  
>      /* Send a minimal RTCP RR */
> -    if (avio_open_dyn_buf(&pb) < 0)
> -        return;
> +    ptr = buf;
> +    bytestream_put_byte(&ptr, (RTP_VERSION << 6));
> +    bytestream_put_byte(&ptr, RTCP_RR); /* receiver report */
> +    bytestream_put_be16(&ptr, 1); /* length in words - 1 */
> +    bytestream_put_be32(&ptr, 0); /* our own SSRC */
>  
> -    avio_w8(pb, (RTP_VERSION << 6));
> -    avio_w8(pb, RTCP_RR); /* receiver report */
> -    avio_wb16(pb, 1); /* length in words - 1 */
> -    avio_wb32(pb, 0); /* our own SSRC */
> -
> -    len = avio_close_dyn_buf(pb, &buf);
> -    if ((len > 0) && buf)
> -        ffurl_write(rtp_handle, buf, len);
> -    av_free(buf);
> +    ffurl_write(rtp_handle, buf, ptr - buf);
>  }
>  
>  static int find_missing_packets(RTPDemuxContext *s, uint16_t *first_missing,
> 
Will apply tomorrow unless there are objections.

- Andreas