[FFmpeg-devel] [PATCH] avformat: add DAT (Digital Audio Tape) demuxer

[Michael Niedermayer]

Hi

On Fri, Jan 17, 2025 at 12:38:02PM +0100, Jerome Martinez wrote:
> Sample files are available at https://archive.org/download/datstrue-read/
> 

>  Makefile     |    1 
>  allformats.c |    1 
>  dat.c        |  159 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 161 insertions(+)
> d8c9ff24544dbf47c46cd3066740ff8fec304d4b  0001-avformat-add-DAT-demuxer.patch
> From 50c78a0ae2049e2dbd65e2c3d28f3d8abea1adfa Mon Sep 17 00:00:00 2001
> From: Paul B Mahol <onemda at gmail.com>
> Date: Thu, 12 Sep 2024 20:34:22 +0200
> Subject: [PATCH] avformat: add DAT demuxer

breaks fate-cdxl-pal8-small

I guess the probe function is not working as expected

[...]
> +static int valid_frame(uint8_t *frame)
> +{
> +    uint8_t *scode = frame+DAT_OFFSET;
> +    uint8_t *subid = scode+7*8;
> +    uint8_t *mainid = subid+4;
> +    int chan_index = (mainid[0] >> 0) & 0x3;
> +    int rate_index = (mainid[0] >> 2) & 0x3;
> +    int enc_index  = (mainid[1] >> 6) & 0x3;
> +    int dataid     = (subid[0] >> 0) & 0xf;
> +
> +    if (dataid != 0 || encoded_codec[enc_index] == AV_CODEC_ID_NONE ||
> +        encoded_chans[chan_index] == 0 ||
> +        encoded_rate[rate_index] == 0)
> +        return 0;
> +
> +    return 1;
> +}
> +
> +static int read_probe(const AVProbeData *p)
> +{
> +    const int cnt = p->buf_size / DAT_PACKET_SIZE;
> +    int score = 0;
> +
> +    for (int i = 0; i < cnt; i++) {
> +        const int ret = valid_frame(&p->buf[i * DAT_PACKET_SIZE]);
> +
> +        score += ret;
> +        if (ret == 0)
> +            break;
> +    }
> +
> +    return FFMIN(score, AVPROBE_SCORE_MAX);
> +}

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Democracy is the form of government in which you can choose your dictator
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