/* * PDV muxer * * Copyright (c) 2026 Priyanshu Thapliyal * * 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 "libavutil/mem.h" #include "libavutil/opt.h" #include "libavutil/rational.h" #include "avformat.h" #include "avio_internal.h" #include "mux.h" #define PDV_MAGIC "Playdate VID\x00\x00\x00\x00" #define PDV_MAX_FRAMES UINT16_MAX #define PDV_MAX_OFFSET ((1U << 30) - 1) typedef struct PDVMuxContext { uint32_t *entries; int nb_frames; int max_frames; uint32_t fps_bits; int64_t nb_frames_pos; int64_t table_pos; int64_t payload_start; } PDVMuxContext; static void pdv_deinit(AVFormatContext *s) { PDVMuxContext *pdv = s->priv_data; av_freep(&pdv->entries); } static int pdv_get_fps(AVFormatContext *s, AVStream *st, uint32_t *fps_bits) { AVRational rate = st->avg_frame_rate; const AVRational zero = { 0, 1 }; if (!rate.num || !rate.den) rate = av_inv_q(st->time_base); if (!rate.num || !rate.den) { av_log(s, AV_LOG_ERROR, "A valid frame rate is required for PDV output.\n"); return AVERROR(EINVAL); } if (av_cmp_q(rate, zero) <= 0) { av_log(s, AV_LOG_ERROR, "Invalid frame rate for PDV output.\n"); return AVERROR(EINVAL); } *fps_bits = av_q2intfloat(rate); return 0; } static int pdv_write_header(AVFormatContext *s) { PDVMuxContext *pdv = s->priv_data; AVStream *st; int ret; if (!(s->pb->seekable & AVIO_SEEKABLE_NORMAL)) { av_log(s, AV_LOG_ERROR, "PDV muxer requires seekable output.\n"); return AVERROR(EINVAL); } st = s->streams[0]; if (st->codecpar->width > UINT16_MAX || st->codecpar->height > UINT16_MAX) { av_log(s, AV_LOG_ERROR, "Output dimensions exceed PDV limits.\n"); return AVERROR(EINVAL); } ret = pdv_get_fps(s, st, &pdv->fps_bits); if (ret < 0) return ret; if (pdv->max_frames < 1 || pdv->max_frames > PDV_MAX_FRAMES) { av_log(s, AV_LOG_ERROR, "The -max_frames option must be set to a value in [1, %u].\n", PDV_MAX_FRAMES); return AVERROR(EINVAL); } pdv->entries = av_malloc_array(pdv->max_frames + 1, sizeof(*pdv->entries)); if (!pdv->entries) return AVERROR(ENOMEM); avio_write(s->pb, PDV_MAGIC, 16); pdv->nb_frames_pos = avio_tell(s->pb); avio_wl16(s->pb, 0); avio_wl16(s->pb, 0); avio_wl32(s->pb, pdv->fps_bits); avio_wl16(s->pb, st->codecpar->width); avio_wl16(s->pb, st->codecpar->height); pdv->table_pos = avio_tell(s->pb); ffio_fill(s->pb, 0, 4LL * (pdv->max_frames + 1)); pdv->payload_start = avio_tell(s->pb); if (pdv->nb_frames_pos < 0 || pdv->table_pos < 0 || pdv->payload_start < 0) return AVERROR(EIO); return 0; } static int pdv_write_packet(AVFormatContext *s, AVPacket *pkt) { PDVMuxContext *pdv = s->priv_data; int64_t offset = avio_tell(s->pb); const uint32_t max_table_gap = 4U * pdv->max_frames; if (offset < 0) return AVERROR(EIO); offset -= pdv->payload_start; if (offset < 0) return AVERROR(EIO); if (pkt->size <= 0) return AVERROR_INVALIDDATA; if (pdv->nb_frames >= pdv->max_frames) { av_log(s, AV_LOG_ERROR, "Too many frames for PDV output.\n"); return AVERROR(EINVAL); } if (offset > PDV_MAX_OFFSET - max_table_gap || pkt->size > PDV_MAX_OFFSET - max_table_gap - offset) { av_log(s, AV_LOG_ERROR, "PDV payload exceeds container limits.\n"); return AVERROR(EINVAL); } pdv->entries[pdv->nb_frames] = ((uint32_t)offset << 2) | (pkt->flags & AV_PKT_FLAG_KEY ? 1 : 2); avio_write(s->pb, pkt->data, pkt->size); pdv->nb_frames++; return 0; } static int pdv_write_trailer(AVFormatContext *s) { PDVMuxContext *pdv = s->priv_data; int64_t payload_size = avio_tell(s->pb); const uint32_t table_gap = 4U * (pdv->max_frames - pdv->nb_frames); int64_t ret; if (payload_size < 0) return AVERROR(EIO); payload_size -= pdv->payload_start; if (payload_size < 0 || payload_size > PDV_MAX_OFFSET - table_gap) return AVERROR(EINVAL); pdv->entries[pdv->nb_frames] = (uint32_t)payload_size << 2; if ((ret = avio_seek(s->pb, pdv->nb_frames_pos, SEEK_SET)) < 0) return ret; avio_wl16(s->pb, pdv->nb_frames); if ((ret = avio_seek(s->pb, pdv->table_pos, SEEK_SET)) < 0) return ret; for (int i = 0; i <= pdv->nb_frames; i++) { const uint32_t frame_off = (pdv->entries[i] >> 2) + table_gap; if (frame_off > PDV_MAX_OFFSET) return AVERROR(EINVAL); avio_wl32(s->pb, frame_off << 2 | (pdv->entries[i] & 3)); } if ((ret = avio_seek(s->pb, pdv->payload_start + payload_size, SEEK_SET)) < 0) return ret; return 0; } #define OFFSET(x) offsetof(PDVMuxContext, x) #define ENC AV_OPT_FLAG_ENCODING_PARAM static const AVOption options[] = { { "max_frames", "maximum number of frames reserved in table (mandatory)", OFFSET(max_frames), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, PDV_MAX_FRAMES, ENC }, { NULL }, }; static const AVClass pdv_muxer_class = { .class_name = "PDV muxer", .item_name = av_default_item_name, .option = options, .version = LIBAVUTIL_VERSION_INT, .category = AV_CLASS_CATEGORY_MUXER, }; const FFOutputFormat ff_pdv_muxer = { .p.name = "pdv", .p.long_name = NULL_IF_CONFIG_SMALL("PlayDate Video"), .p.extensions = "pdv", .p.priv_class = &pdv_muxer_class, .p.audio_codec = AV_CODEC_ID_NONE, .p.video_codec = AV_CODEC_ID_PDV, .p.subtitle_codec = AV_CODEC_ID_NONE, .priv_data_size = sizeof(PDVMuxContext), .p.flags = AVFMT_NOTIMESTAMPS, .flags_internal = FF_OFMT_FLAG_MAX_ONE_OF_EACH | FF_OFMT_FLAG_ONLY_DEFAULT_CODECS, .write_header = pdv_write_header, .write_packet = pdv_write_packet, .write_trailer = pdv_write_trailer, .deinit = pdv_deinit, };