On 4/15/2017 10:36 AM, James Darnley wrote:
> ---
> libavformat/Makefile | 1 +
> libavformat/allformats.c | 1 +
> libavformat/falcom_xa.c | 98
> ++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 100 insertions(+)
> create mode 100644 libavformat/falcom_xa.c
Changelog/version.h/etc before you push.
>
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index 6bdfbe6789..06b6b5da57 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -158,6 +158,7 @@ OBJS-$(CONFIG_EA_DEMUXER) +=
> electronicarts.o
> OBJS-$(CONFIG_EAC3_DEMUXER) += ac3dec.o rawdec.o
> OBJS-$(CONFIG_EAC3_MUXER) += rawenc.o
> OBJS-$(CONFIG_EPAF_DEMUXER) += epafdec.o pcm.o
> +OBJS-$(CONFIG_FALCOM_XA_DEMUXER) += falcom_xa.o
> OBJS-$(CONFIG_FFM_DEMUXER) += ffmdec.o
> OBJS-$(CONFIG_FFM_MUXER) += ffmenc.o
> OBJS-$(CONFIG_FFMETADATA_DEMUXER) += ffmetadec.o
> diff --git a/libavformat/allformats.c b/libavformat/allformats.c
> index 09e62c3cfc..0c23ea9df0 100644
> --- a/libavformat/allformats.c
> +++ b/libavformat/allformats.c
> @@ -117,6 +117,7 @@ static void register_all(void)
> REGISTER_MUXDEMUX(EAC3, eac3);
> REGISTER_DEMUXER (EPAF, epaf);
> REGISTER_MUXER (F4V, f4v);
> + REGISTER_DEMUXER (FALCOM_XA, falcom_xa);
Maybe just Xanadu?
> REGISTER_MUXDEMUX(FFM, ffm);
> REGISTER_MUXDEMUX(FFMETADATA, ffmetadata);
> REGISTER_MUXER (FIFO, fifo);
> diff --git a/libavformat/falcom_xa.c b/libavformat/falcom_xa.c
> new file mode 100644
> index 0000000000..4c5f32a1b6
> --- /dev/null
> +++ b/libavformat/falcom_xa.c
> @@ -0,0 +1,98 @@
> +/*
> + * Falcom Xanadu demuxer
> + * Copyright (c) 2016 James Darnley
2017?
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
> USA
> + */
> +
> +#include "avformat.h"
> +
> +typedef struct FalcomXADemuxContext {
> + const AVClass *class;
> + unsigned frame_size;
> +} FalcomXADemuxContext;
> +
> +static av_cold
> +int falcom_xa_read_header(AVFormatContext *s)
A probe function should be added if possible.
> +{
> + int sample_rate, bit_depth, channels;
> + AVStream *st;
> + AVIOContext *pb = s->pb;
> +
> + avio_seek(pb, 22, SEEK_SET);
avio_skip() is more in line with most demuxers.
What are those first 22 bytes? I assume header magic (which you should
check in a probe function) and maybe some version byte?
If the latter, better check it here.
> + channels = avio_rl16(pb);
> + if (channels != 2)
> + return AVERROR_INVALIDDATA;
If there are real world files with more than two channels, you could
instead return PATCHWELCOME and even ask for a sample.
> +
> + sample_rate = avio_rl32(pb);
> + if (sample_rate != 44100)
> + return AVERROR_INVALIDDATA;
Same.
> +
> + avio_seek(pb, 34, SEEK_SET);
avio_skip().
> + bit_depth = avio_rl16(pb);
> + if (bit_depth != 16)
> + return AVERROR_INVALIDDATA;
> +
> + avio_seek(pb, 44, SEEK_SET);
Same.
> +
> + st = avformat_new_stream(s, NULL);
> + if (!st)
> + return AVERROR(ENOMEM);
> +
> + st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
> + st->codecpar->codec_id = AV_CODEC_ID_ADPCM_MS;
> + st->codecpar->sample_rate = sample_rate;
> + st->codecpar->channels = channels;
> + st->codecpar->block_align = 2048;
> +
> + return 0;
> +}
> +
> +static
> +int falcom_xa_read_packet(AVFormatContext *s, AVPacket *pkt)
> +{
> + FalcomXADemuxContext *ctx = s->priv_data;
> +
> + if (ctx->frame_size == 0) {
> + unsigned tell = avio_tell(s->pb);
avio_tell() returns int64_t.
> + unsigned size = avio_rl32(s->pb);
> + av_log(ctx, AV_LOG_DEBUG, "read size %u (0x%x) at offset %u
> (0x%x)\n",
> + size, size, tell, tell);
> + if (size % 2048)
Nit: size & 2047.
> + return AVERROR_INVALIDDATA;
> + ctx->frame_size = size;
> + avio_skip(s->pb, 4); // unknown bytes
> + }
> +
> + ctx->frame_size -= 2048;
> + return av_get_packet(s->pb, pkt, 2048);
> +}
> +
> +static const AVClass falcom_xa_demux_class = {
> + .class_name = "Falcom Xanadu demuxer",
> + .item_name = av_default_item_name,
> + .version = LIBAVUTIL_VERSION_INT,
> +};
> +
> +AVInputFormat ff_falcom_xa_demuxer = {
> + .name = "falcom_xa",
> + .long_name = NULL_IF_CONFIG_SMALL("Falcom Xanadu demuxer"),
> + .priv_data_size = sizeof(FalcomXADemuxContext),
> + .read_header = falcom_xa_read_header,
> + .read_packet = falcom_xa_read_packet,
> + .priv_class = &falcom_xa_demux_class,
No known extension/s? And did you try using AVFMT_GENERIC_INDEX flag
to see if it enables seeking without a custom read_seek() function?
> +};
>
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